Michael Walker, SDA
“Propeller are awesome. They have the best turn-around time of any supplier I deal with. Their email system is exceptionally easy to use and comes with all sorts of nifty reporting features that allow you to track how your campaigns are faring.”


We've compiled a list of answers to some of the questions we are asked most frequently in regards to email marketing. If you have further or more in depth questions, please contact us, we're more than happy to help.

What are the benefits of outsourcing my email delivery?

Many companies and clients wonder what benefits an external email service provider can offer them, and whether they could just do it in-house themselves.

Easily measure the success of your campaigns

If you know who opened your emails, what they clicked on, who bounced and who unsubscribed, you can start to understand who your audience really is, and what they are interested in.

For every campaign you send, PropellerMail automatically creates reports that are:

  • Easy to understand
  • Automatically updated
  • Simple to share with other people

Save time

What administrative work?

Sending the email might not take too long (although it may crush your mail systems internally!). It’s dealing with the results of your campaign that can eat up your time.

Subscribe and unsubscribe requests

every time you send a campaign, some people are likely to want to get off the list. It may only take you a minute or two to deal with, but if you need to stop what you are doing and switch tasks, it adds up quickly. And what happens if you miss one and send to that person again?

PropellerMail lets people unsubscribe instantly from any email they receive, and your list is updated automatically.

Dealing with bounced emails

For any given campaign, you might expect up to 10% of the emails to be bounced back to you. That could be hundreds or thousands of emails you need to handle somehow.
Are they permanent bounces? Then should you remove them from your list? Or do you need to resend the email to them?

PropellerMail instantly removes hard bounces, and re-sends your campaigns automatically to addresses which soft bounce.

Dealing with spam complaints

Sometimes people forget that they signed up for your emails, and hit the spam button. PropellerMail instantly removes people from your list when they make a spam complaint, ensuring they do not receive any more email.

Avoid hold ups on your own mail servers

We’ve heard of more than one marketing manager staying up till all hours trying to send email campaigns out without shutting down the company email network.

Let our servers handle that load for you.

Improve your deliverability

Your email campaign can only succeed if your recipients are actually able to read it. Using PropellerMail to send your campaigns can have a big impact on the number of people receiving the emails.

Whitelisting and feedback loops

We have relationships with major ISPs like AOL, Hotmail, Yahoo! and many more that mean our mail servers are recognized as legitimate senders of bulk email, so your campaigns have a much greater chance of being delivered.

Monitoring of blacklists

We continually check blacklisting services to make sure our servers are not being listed, something which is time consuming and complex to do for your own servers.

Specialized network of mail servers

Our mail servers optimize email delivery for particular recipient mail systems, throttling the speed of delivery to match acceptable levels for each system.

Use advanced options and smarter features


Use custom fields to adapt your emails for individual subscribers


Send focused emails to subsets of your full lists

Powerful import and export

Easily get your subscriber lists into and out of the system at any time

Archive your campaigns

Easily display your previous campaigns on your website

Constant improvement

A web based service like PropellerMail can be updated with better performance, new features and smarter tools very quickly, and at no extra cost. You don’t have to worry about having the wrong version, or getting out of date.

Every month we are adding features and making updates to make PropellerMail do more for you in less time.

Secure, reliable and supported

Your valuable subscriber information and campaign details are kept safe in our data centers. With biometric security, uninterruptible power supplies and environmental control units, our physical security and reliability is state of the art.

We keep your data backed up and duplicated across our network at all times. Our hardware is completely redundant, meaning that even if one disk or server fails, nothing will be lost and the system will stay up.

Focus on your customers, not on your technology

Sure, you can use your own email client, or some other in-house tool to add your subscribers and deal with unsubscribe requests and bounces from bad emails all day.

But wouldn’t you rather spend that time working on the email itself, crafting the message to better meet your customers requirements and tweaking subject lines and headlines to get better results?

Using an email service provider lets you avoid the mundane administrative work and concentrate on serving your customers better.

How do I know who I can and can't send to

By far the most important aspect of email marketing is the concept of permission. It’s the only thing separating you from the spammers of this world, but for many it remains a grey area. It doesn’t need to be. First of all, let’s clarify what spam is, and then what kind of permission you and your clients will need to use PropellerMail.

This is so important, because if you don’t comply, not only will we be forced to close your account, you could land yourself in legal trouble

Being ‘legal’ is not enough - our definition of spam

While the CAN-SPAM laws are a step in the right direction for classifying and reducing spam, we don’t feel they go far enough. Our definition of spam goes beyond the laws in most countries and encompasses what we believe to be true permission email marketing.

Spam is any email you send to someone who hasn’t given you their direct permission to contact them on the topic of the email.

But that’s not enough. Permission is a fuzzy word open to interpretation. Let’s get into some specific scenarios so it’s clear what does and doesn’t constitute permission.

The type of permission you MUST have

You can only email subscribers using PropellerMail if you obtained their permission in any of the following ways.

  • They opted in via your web site

    This could either be through a newsletter subscribe form or by ticking a checkbox on another form. This checkbox cannot be checked by default and it must clearly explain that checking it will mean you will be contacting them by email.

  • They completed an offline form and indicated they wanted to be emailed

    If someone completes an offline form like a survey or enters a competition, you can only contact them if it was explained to them that they would be contacted by email AND they ticked a box indicating they would like to be contacted.

  • They gave you their business card

    If someone gives you their business card and you have explicitly asked for permission to add them to your list, you can contact them. If they dropped their business card in a fishbowl at a trade show, there must be a sign indicating they will be contacted by email about the specific topic.

  • They purchased something off you in the last 2 years

    By making a purchase from you they have provided their permission implicitly. Feel free to email them but at the same time, we think it’s always better to ask anyway, so why not include an opt-in checkbox as part of the checkout process.

Scenarios that DON’T equate to permission

Basically, anything outside the examples above doesn’t equal permission in our eyes, but here are some examples to make sure we’re crystal clear.

  • You obtained the email addresses from a third party

    Whether you purchased a list, were provided one by a partner or bought a bankrupt competitor’s customer list, those people never gave YOU permission to email them and they will consider your email spam. No matter the claims of the source of this list, you cannot email them with PropellerMail.

  • You scraped or “copy and pasted” the addresses from the Internet

    Just because people publish their email address doesn’t mean they want to hear from you.

  • You haven’t emailed that address for more than 2 years

    Permission doesn’t age well. Even if you got their permission legitimately, they won’t remember giving it to you. If you haven’t sent something to that address in the last 2 years, you can’t start now.

Permission Guidelines Handout

To help you ensure you stay on the right side of the line, we've put together a Free Permission Handout.

What do the terms in the Campaign Snapshot like bounced, opened, etc actually mean?

Email results pie chartThe Campaign Snapshot contains a number of important terms which explain the most recent results for each campaign you send.

Unique Opens

This is the total number of recipients that we recorded as opening your campaign.

Not Opened

This is the total number of recipients for whom we did not record an open or click.


The Clicks data provides a number of important figures about the links in your campaign. As an example, "2,481 (14.28%) recipients clicked 7 links" tells us the following:

  • A total of 2,481 recipients clicked at least one link.
  • This resulted in a click-through rate of 14.28%.
  • All up, 7 different links in the campaign were clicked.


This is the total number of recipients that clicked the unsubscribe link in the campaign.


This is the total number of recipients that bounced and also provides you with the percentage of recipients that bounced.


The delivered count tells you the total number of emails that were successfully delivered to your recipients. It is equal to the total number of messages sent minus the total number that bounced back. The delivered percentage tells us the total percentage of messages that were successfully delivered.

What is an open rate

Open rate is a measure of how many people on an email list open (or view) a particular email campaign. So a 20% open rate would mean that of every 10 emails delivered to the inbox, 2 were actually opened.

How do you measure opens?

We automatically add a piece of code to each campaign that requests a tiny, invisible image. When a reader opens the email, the image is downloaded, and we can record that download as an open for that specific email.

It is important to understand that the open rate is not a 100% accurate measure. Recording an 'open' can only happen if the readers email client is capable of displaying html with images, and that option is turned on. Similarly, people reading your html email without images showing will not be recorded as opens (unless they click a link).

Your readers may also have a preview pane in their email client which might be displaying your email automatically (and therefore downloading the images) without the reader ever having to click on it or read it.

So you should never take your open rate as a hard and fast number, because you can never know the true figure. It is much better used as general guide, and as a way of measuring the trends on your email campaigns.

What is a typical open rate?

Really, there is no typical open rate. The rate obtained for any list, or group of lists will depend on how it was measured, when it was sent, the size of the list and a zillion other potential variables.

There are certainly some broad trends in open rates.

  • As list size goes up, the open rate tends to fall; possibly because smaller companies are more likely to have personal relationships with their list subscribers.
  • Companies and organizations that are focusing on enthusiasts and supporters, like churches, sport teams and non profits see higher open rates
  • More specific niche topics, like some manufacturing areas also typically have higher open rates than emails on broader topics

So what if you just have no idea of what is a reasonable open rate? Based on everything we have seen, and on the other research out there, the bottom line is this:

If you are getting an open rate between 20% and 40%, you are probably somewhere around average.

Very few lists of reasonable size are getting much above 50% open rates from normal campaigns. Your list may have some specific factors that give you higher rates; if so, well done.

Why do I have such a high number of bounces in my campaign?

This typically happens on your first campaign and is common when you’re using older established client lists. Let’s say you have a mailing list that’s slowly grown over the years but hasn’t been contacted in 12 months or so.

Things start to get ugly

The campaign’s sent. 40% of your list hard bounce right from the word go. Another 25% unsubscribe immediately.

30% is a big number

Email address churn averages about 30% every year. This means that each year almost a third of your subscriber list will have moved on to a new email address. If you haven’t sent to your subscriber list in a while, you can see how quickly they can become out of date.

Typo’s are common errors

A number of bounces will result from simple data entry errors – missing underscores, upper or lower case, missing full stops, names spelt incorrectly etc etc.

Will we have a chance to repair the list?

Of course. Using your bounced list, you can check that the email addresses are correct and if they are, perhaps contact your subscriber to check the email address or obtain their new email address – the most likely scenario is that they simply changed their email address or ISP.

Further information regarding the different types of bounces can be found be clicking on ‘tell me more’ in the bounce results panel.

How do I reduce the number of emails that bounce?

Managing the way you handle bounces for your Subscriber Lists has never been more important. Keeping a close eye on your bounces can reduce your email delivery costs, therefore having a direct impact on the ROI of your campaigns.

Firstly, some definitions:

A soft bounce is an email message that gets as far as the recipient’s mail server (it recognizes the address) but is bounced back undelivered before it gets to the intended recipient. A soft bounce might occur because the recipient’s mailbox is full, the server is down or swamped with messages, the message is too large or the user has abandoned the mailbox. Most email service providers will attempt to deliver the email regularly for a few days. If it is still undelivered, it becomes a hard bounce.

A hard bounce is an email message that has been returned to the sender and is permanently undeliverable. Causes include invalid addresses (domain name doesn’t exist, typos, changed address, etc.) or the email recipient’s mail server has blocked your server. Servers will also interpret bounces differently, meaning a soft bounce on one server may be classified as a hard bounce on another.

PropellerMail automatically moves subscribers that hard bounce into a “Bounced Subscribers” category, so they don’t receive future campaigns. You can also customize how soft bounces are handled for each subscriber list.

Here are some quick tips on ways you can reduce bounces even further:

  1. Keep your subscriber lists clean
    PropellerMail automatically removes invalid email addresses as you add them, but when new subscribers sign up via a subscribe form, they may enter an invalid address. Check each list for incorrectly formatted addresses, invalid domains and typos.
  2. Use double opt-in
    When creating a subscriber list, set it as double opt-in, allowing each address to be validated by the subscriber before it can be added to your list.
  3. Monitor Delivery Rates By Domain
    Track your open and bounces rates by major domain, such as AOL, Hotmail, Yahoo, Earthlink and others. If one is significantly different than the others, or your experience a sudden change, your campaign may be getting caught by spam filters.
  4. Understand and Monitor Spam Filters
    Get to know the more common things that most spam filters look for and make sure you avoid them in each campaign you send.
  5. Test Your Emails
    Prior to sending your campaign to your entire list, send a test to yourself and others. Make sure you try and include all the major types of email clients used by members of your list when testing.
What are some good methods for avoiding spam filters?

Even when you’re sending an email campaign to subscribers who opted-in, your email can still be flagged as spam by overzealous spam filters which seem to be getting more and more aggressive with their spam flagging analyses. Simply using the word “free” in an email message can often land you in the spam heap.

Here are some simple tips and techniques you should consider when writing and designing your campaigns:

  1. Keep sender addresses as short as possible.
  2. Avoid continuous sending of messages to full or invalid mailboxes. You can do this by tweaking your bounce handling settings for each subscriber list.
  3. Minimize the use of these words and phrases in the subject line, message body, sender address, and reply-to address:
    • Use of the word Free (although “free” tends to have more leeway than most other trigger words), $$, XXX, sex or !!! (any excessive punctuation)
    • Subject contains “Double Your”, “?”, “For Only” or “Free Instant”.
    • Email contains at least 70 percent blank lines
    • The from field appears to not contain a real name, ends in numbers or contains the word friend.
    • The reply to field is empty
    • The email claims not to be spam
    • The email contains excessive images without much text
  4. Monitor new subscribers in your lists. Set suspicious “spamflag” addresses such as “abuse@” or “marketerspam@” as Inactive subscribers.

Ultimately, the most important thing you can do is adhere to best practices for email marketing. Gain permission, compose relevant content, and deliver messages according to the customer’s needs, wants, and preferences.

What’s the best day and time to send my email newsletters?

Firstly, let’s look at what some of the more popular research out there is telling us. Just keep in mind that this research is conducted across a range of markets, so it might not always be right for you or your recipients.

In July 2004, delivery consultancy Return Path analysed over 3.4 million email messages and found that email sent on Monday was more likely to get opened, and anytime between 6am and 10am was the best time of the day to send.

More recently however it has been revealed that this might no longer be the case and that emails sent from Wednesday to Friday maximized open rates.

So which one’s right for you?

The truth is, the optimal delivery time will depend on what you’re sending and who you’re sending to.

Luckily, one of email’s strengths is it’s just so testable (is that a word?). You should use the time of day and day of week as variables in your tests. Try splitting your subscribers into 2 separate subscriber lists and sending to one half at one day and time and one half at another. Run a comparison of your results in the Reports section and learn from what you see.

Running tests like this over the course of a few campaigns is the only way to really know when you should and shouldn’t be sending.

What is image blocking?

Many people, either by email client defaults or personal preference, are blocking images in the HTML-formatted messages they are accepting. And then there are a small number of people who block HTML entirely. According to a study by Epsilon Interactive 30% of your recipients don’t even know that images are disabled. In any case, it’s logical for recipients to block images and good practice for us to prepare for this scenario.

So what happens to our emails when images are blocked? What are the best practices for ensuring accessibility and optimizing presentation therein? What are default settings across the board? Let’s get down to answering these questions.

Default email client settings

Every client has its own default settings regarding displaying/hiding images. And while most email clients have a setting to turn images on or off, some offer conditional settings which are contingent upon known senders or other factors.

Recommendations for Successful Deployment

From a designers perspective, an email is successful when it meets the following goals:

  • Retains visual integrity in the most commonly used email clients with images enabled.
  • Retains readability in the most commonly used email clients with images disabled.
  • Is readable to people with visual disabilities and navigable to people with mobility disabilities.
  • Is low in weight for recipients using mobile devices and dial-up connections.
  • Is deployed to a permission-based list of subscribers.
  • Meets CAN-SPAM Act requirements.
  • Legitimately passes common tests employed by spam filters.

Looking at this list it becomes clear just how important it is to consider image blocking when designing/developing an email. Dependency on images can lead to failures on many different levels. Preparing for a scenario in which images are disabled puts us at an advantage to oblige the settings/preferences of a broader range of recipients.

Become a “Known Sender”

Nearly every email client in my test suite enables people to automatically display images when a message is from a “known sender” (senders appearing in white lists, contact lists or address books). Because our subscribers have requested to receive emails from us, they will naturally want to ensure they receive the messages. Spam filters can disrupt legitimate communication when subscribers are unaware of how they function. With a couple, simple notifications we can increase our chances of success:

  1. Ask a subscriber to add the email-list address to their address book (right on the subscribe form) and briefly explain why.
  2. Enable a double opt-in subscription process, and send a plain-text confirmation which includes a request to add the email-list address to a recipient’s address book. And, again, briefly explain why.

Informing a subscriber about this simple step will increase our chances of images being enabled and will help us legitimately pass through spam filters.

Prepare for Disabled Images

So we’ve created a structurally-sound template, we’re preparing to send our email to a permission-based list of subscribers and we’ve taken steps to see our list email-address into the address books of the said subscribers. There are still a number of people on our lists who will intentionally block images, and therefore we should account for that scenario.

There are some things we can do to retain the integrity of our emails when images are disabled:

  1. Begin an email with HTML text or logical ALT text. We can decide what a reader sees in a preview pane or small message-window. If we’re prepared, we can optimize the experience of scanning messages. Moreover, some applications offer the ability to preview the first few lines of text before an email is loaded/viewed.
  2. Use ALT attributes. This seems so obvious, but we don’t have enough fingers and toes to count the email newsletters we see without them, so there it is.
  3. Use captions for contextually-important images. In lieu of proper support for ALT attributes across the board, we can add captions to images which are vitally important to the content of an email.

Avoid Image-Based Emails

Again, this is something which should seem obvious. But image-based emails are often practiced as a simple, easy method of delivering a pretty design irrespective of the rendering circus among the array of common email-clients. When we ponder image blocking as part of the rendering equation, it’s easy to see how an image-based email could be completely destroyed with a single preference. Furthermore, this doesn’t take into consideration file sizes for mobile/dial-up recipients, accessibility for those visually impaired or the HTML-to-text ratio that popular spam filters apply with their algorithms.

In summary, we should be giving serious consideration to image-blocking and what we can do about it. It’s natural and reasonable why people disable them, but with the right approach we can improve the experience for our subscribers.

Can I use flash in my email newsletters?

You’re putting together a newsletter and want to jazz it up by adding some flash to the email? You might be left wondering, is that going to work?

Well the short answer is, probably not. By default, AOL, Outlook, Outlook Express, Thunderbird and Eudora will not display flash movies in a HTML email because the security settings prohibit controls like flash from running. On the other hand, Mac Mail has no problem displaying flash.

What about web-based email clients such as Yahoo!, Gmail and Hotmail? They load emails in your browser, which we know can display flash, so surely they work? Unfortunately, the answer is no again, as these providers automatically strip out any flash content in your campaign.

So what’s the solution? Unless you know exactly what your recipients are using to read their email, and you’re positive it can display flash, the answer is pretty obvious, don’t include it in your emails. If the flash is important to the campaign, you can always create a link to it from your email and users will be able to view the flash from their browser.

Update: We ran a series of tests across the most common email environments to test flash support. Our verdict: Nothing’s changed, stay away from flash.

Can I use forms in my email newsletters?

Email clients consider email forms to be a security risk. While some email clients simply warn you of potential danger, others outright disable the forms. So if you want to send out a form, you should know that most of your recipients will never be able to use it. And for those who can, they’ll think twice about submitting data when they see a warning from their email client.


Given the sporadic support for forms in emails, we recommend linking to a form on a website rather than embedding it in the email. This is the safest, most reliable solution to pairing an email message with a form. More people will see it and be able to use it, and as a result participation will increase.

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