The Awful World of Email Deliverability

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It’s not enough to just design a good email template. You also have to put in the work to make sure your email gets delivered. Fortunately, there are a lot of great services to help make this happen.

Understand Email Deliverability

First, let’s go over how your email gets delivered. This is going to be an overly simplified view – after all, I write for product teams not engineering teams. But it should give you enough background to know what you need to consider if you plan to send a lot of email through your product. Beware, this is one of my more technical posts. But don’t fret, you can handle it.

When you send an email to someone, your email gets sent to their service provider (ie. Gmail, Yahoo, Comcast, etc.). The service provider tests the email against its service-wide spam filters. If it passes, it then routes the email to the appropriate mailbox.

If the recipient views their email through a 3rd party client (i.e. Outlook or Mail.app), the client also runs the message through it’s own spam filters. If it passes through those, it makes it’s way to the recipient’s inbox.

Finally, the recipient may also manually flag the message as spam.

Throttling, Whitelisting, and ISPs, Oh My!

Knowing this, how can you make sure your email clears these hurdles and makes it to your recipient’s inbox?

First, you need to make sure that you aren’t sending email too fast. Each ISP has its own rules about how fast you can send email to their mailboxes.

Rather than managing all of this yourself, you should probably use a 3rd party provider to throttle your outgoing mail. Rather than directly sending your email, your product should queue up outgoing messages via a throttling service. The throttling service will then send out email at an acceptable rate according to the wishes of each ISP.

However, even with a throttling service, things can go wrong. Inevitably, if you send enough email (it doesn’t take very much), you’ll get flagged as spam or in violation of an ISPs email policy. In this case, the service may temporarily stop receiving email from you. This means the service will stop forwarding your emails to their users’ inboxes. You’ve been blacklisted. Not good.

Most of the time, when you get blacklisted, it’s as easy as making a phone call or sending an email to clear up the issue. ISPs will want to know what your product does, may have some questions about your business, and will want a general idea of how much email they should receive from you.

If you pass their evaluation, you’ll get what’s called, whitelisted. Basically, they are saying by default they trust you and will deliver your email, unless you do something egregious. Don’t do anything egregious. And of course, there are a number of whitelisting services that can help you get whitelisted with the major email providers.

Of course, every ISP differs on what they define as egregious. And who you send to can impact this. Some ISPs are more notorious than others. AOL comes to mind. Comcast also can be pretty sensitive. However, regardless of the ISP, if enough of their users mark your messages as spam, you can get blacklisted. More on that later.

Not too long ago, if you sent a large volume of email, you used to have a  full-time person working on your email reputation. Fortunately, the world is changing quickly and high-volume email is becoming the norm. Now if you know what you are doing and set things up right, you can send a large volume of email without too much trouble, as long as you take advantage of professional throttling and whitelisting services.

Getting Past The Spam Filters

If you play nice and follow all the rules, you move to the next step. You have to make it through the server-side and the client-side spam filters.

First, get up to speed on CAN-SPAM, legislation from 2003 that dictates what’s acceptable. Here are the critical elements:

• make it easy for people to unsubscribe
• remove someone from your list within 10 days of them unsubscribing
• use a from line and subject line that accurately represents your content
• include the physical address of your business in the email
• don’t muck with your email headers.

Of course, no legislation is that simple. You can learn more here.

Second, don’t send spam.

No really. Get up to speed on the latest spam techniques and avoid them at all costs. Remember, only send high quality email.

Third, run your emails through a spam scorer. This will give you an idea of whether or not your email is going to get flagged en masse. Many mail systems use some variant of spam assassin. Test your messages against their spam rules before you send. Also test in GMail and the oner large email services.

The Curse of Marked As Spam

Finally, you need to work to make sure that your recipients don’t mark your messages as spam. If enough recipients from the same ISP do this, it can trigger a rule on the server-side that will prevent the ISP from delivering your mail to all of their users, not just the users who marked your messages as spam.

To prevent recipients from marking your messages as spam, make it clear why they received your message and make it dead simple for them to unsubscribe.

The Best Path to Email Deliverability … Manage Your Recipient List

Of course, the best way to get your email delivered is to make sure you are sending to people who want to receive your messages. Keep your recipient list up-to-date.

What does this mean? Start by handling bounces. An email “bounces” when the receiving server can’t deliver the email. There are hard bounces and soft bounces. A hard bounce means the server can’t deliver the message. It can’t recognize the recipient or the email address is no longer in use. You should remove hard bounces from your mailing list.

Soft bounces usually indicate that the server temporarily can’t deliver your email. Maybe the recipient’s inbox is full. Or perhaps they’ve temporarily setup a rule rejecting all email. You don’t need to remove soft bounces from your mailing list right away. But you should track them and remove addresses that repeatedly bounce. This will improve your reputation with the mail service.

And once again, you don’t want to send email to people who don’t want it. So make it easy for someone to unsubscribe to your messages.

You Don’t Have To Do It Yourself

Fortunately, email deliverability is getting easier and easier. With services like SendGrid, StrongMail, and even Return Path, there’s little you’ll have to do yourself, other than make sure that you have the right services lined up.  So do some research before you start solving these problems yourself.

How do you handle bulk product emails? Please share in the comments.