Skip to main content

Email bounce rates vary even when sending to the same list in the same week

Hi there!

We have a weekly newsletter that goes out once a week (Monday at noon) to a list of all of our Massachusetts supporters. We also send that same list of supporters action alerts and fundraising appeals -- usually one or two a week. 

I'm finding that the bounce rates can vary considerably within the same week, even if we're using the same list and haven't added any new supporters. This week, for instance, we sent our newsletter to 5,100 people and had only 4 emails bounce, which seemed pretty good. Then, just one day later, I sent an action alert to the exact same list (no new subscribers), and had 16 emails bounce. Any idea why that could be? 

We didn't get any spam complaints on this week's newsletter. In general, we get an average of 1-2 spam complaints a week, and send a total of 10,000-15,000 messages (two-three blasts sent to 5,000 people each). 

The spam score for the newsletter was HIGHER (1.1) than the spam score for the action alert. Is a spam score of 1.1 enough to cause problems?

Any idea what could be happening?

Thanks! 

Official response from

Bounces are never good for your email list, because of the negative impact it has on email deliverability and the overall success of email campaigns. It's additionally frustrating because bounces can happen for a number of different reasons like:

Non existent email address - email address could have a typo or the person with the address has left the organization

Undeliverable email - email server is temporarily unavailable, overloaded, or couldn’t be found

Mailbox full - if contact has so many emails in their inbox that they can’t receive any more, your emails will bounce back until there’s space for them; or contact is no longer using that email address

Vacation/Auto Reply - If someone goes on vacation or can’t check their email, your emails to them will bounce. However, your message actually did get delivered

Blocked email - The receiving server has blocked the incoming email. (This happens a lot with government institutions or schools, where servers are strict when it comes to receiving email).

The best way to troubleshoot is to look at the error messages associated with your bounces to see what is actually going on. You can find the error messages on your email blast under Dashboard > Bounced.

Share this post

Showing 1 reaction

How would you tag this suggestion?
Please check your e-mail for a link to activate your account.