Top 10 Things That Hurt Your Email Delivery

By April 1, 2019 One Comment


Emails are sent using an MTA (Mail Transfer Agent), which is essentially a piece of software that connects one computer to another to send email. In order for everybody to understand each other, a standard was established called RFC (Request For Comments) and every email in the world must be RFC-Compliant in order for the message to be delivered successfully. It doesn’t matter if the message is in English, French or Chinese, a successful transfer must include the following:

HELO/EHLO (introduction)
DATA (body of the message)
QUIT (end of the message)
221 Goodbye

As is the case with most ESPs, sending multiple copies of the same message can be achieved within the same connection thus allowing you to send to multiple recipients at once. This is done by repeating the RCPT TO command several times within the same connection, but there are limitations. For example, some ISPs limit the number of recipients and can also limit the number of connections per IP within a certain timeframe, this process is called “throttling”.

Luckily you don’t have to worry about this, we have a trained group of individuals who are looking after this for you. Leave this part up to us!

Take away: If my computer doesn’t say the right things to your computer, there is little hope that you will accept my email.


If your recipients are marking your email as ‘spam’, your delivery is going to be in trouble. Spam reports are a direct reflection of how your email is received and what a lot of people don’t understand is CAN SPAM and Bill C-28 aren’t the gatekeepers; the ISP is, and the ISP listens to their users (your recipients).

If you want your email to get delivered, you cannot generate complaints. It’s as simple as that. Here are a few ways to avoid user complaints:

  • Make sure every person on your list knows who you are and is expecting your email
  • Send a confirmation email to all new signups (if you are not doing this, you are in the dark ages of email marketing.. seriously)
  • Have the common courtesy to ask people if they want to be on your mailing list, DO NOT sign them up automatically
  • Make your signup process crystal clear, explaining what someone is signing up for, when they will start receiving emails, and how often they can expect to hear from you

For a more complete list, check out our Guide to Understanding Email Deliverability here.

Take Away: If people don’t want to receive your email or never wanted to receive it in the first place, they are going to complain.


A ‘hard’ bounce is generated when you try to send an email to an address that does not exist. Sending to these invalid addresses repeatedly (whether knowingly or not) will seriously damage your delivery. You must ensure they are removed and stay removed.

If you haven’t used the list in a while (3-6 months) or you are thinking of reviving an old list, you need to be very careful. ISPs monitor the number of hard bounces you generate very closely and too many will affect your delivery and cause blocks.

  • Confirm the address exists on signup by sending a confirmation email
  • Ensure you are processing hard bounces correctly
  • Send on a regular basis

Take Away: If you aren’t removing the bad eggs from your hen house, it’s going to get pretty stinky.

Spam Traps

Spam traps are email addresses used to catch spam. They do not signup to receive email voluntarily and if they wind up on your list, it is going to affect your delivery, your reputation or worse.. get you blacklisted. Believe it or not, spammers have ways to get around complaint/bounce rates, but they do not have ways to get around sending to spam traps.

  • Never purchase, borrow, steal or harvest an email list
  • Confirm new signups to ensure the person signing up owns the address in question
  • Remove hard bounces
  • Send on a regular basis

Take Away: Traps addresses are one of the most effective ways of controlling spam today, they are not going anywhere. If you don’t protect yourself, you are at risk.


OK, now that we’ve covered the easy part ☺ .. here’s where it gets interesting. Making sure your recipients open and read your emails!

ISPs measure engagement by looking at the number of people who open and click your emails. Engagement is nothing new, it’s been around for a while but like everything, ISPs need to make sure it works before acting on it. Guess what? Now they’re acting on it.

Take Away: If people aren’t actively opening/reading/clicking on links in your emails, it’s a pretty good sign they aren’t interested in receiving them.

This covers the first five of our top ten reasons – check back next week for the remaining five!

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Author Kevin Huxham

More posts by Kevin Huxham

Join the discussion One Comment

  • Jim says:

    I like the way you talked about spam traps. They are in fact the best way to catch people sending unsolicited commercial email. We have also seen mailers who are very sophisticated in that they study DNS and conversations to decipher where the traps are in the list and try to remove them. It seems like it is an ongoing battle.

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