Understanding Mailbox Full, Vacation/Auto Reply, and Other Bounces


Updated May 2024


Here at Constant Contact, we are an industry leader in email delivery. This is no accident. Our Terms and Conditions are designed to ensure the best possible delivery rate for all of our customers.


That being said, it’s expected (read: absolutely normal) that most email campaigns will have some level of bounces. Knowing the cause and reasons behind these bounces can help you as a marketer to ensure you are mailing to the cleanest, most engaged list that you can. First, I covered Non-Existent and Suspended bounces, then Undeliverable and Blocked bounces; today I will be going over the remaining categories: Mailbox Full, Vacation/Auto-Reply, and Other.


What Is A Mailbox Full Bounce?

When an inbox reaches it’s maximum allowed storage, it will reject the message and bounce it back to Constant Contact as “Mailbox Full.”


If The Recipient Frees Up Space In Their Inbox, Will They Start Getting Mail Again?

Yes; however, I recommend removing these contacts. Here’s why- most ISPs (Internet Service Providers) provide more than enough inbox space for the average user. If someone’s inbox is so full that they can not accept mail, chances are they are not actively checking their mail and therefore are not an engaged contact.


What’s The Deal With The Vacation/Auto-Reply Bounces? When I Set An Auto-Reply, The Mail Waits For Me In My Inbox.

You’re right! This is the exception to the rest of the bounce rules. Messages that show in this category are delivered to the contact, no action on your part is necessary. We include these with the bounces to let you know that you may not see an open/response/click from this customer for a while.


Note: While most of these responses get sent to the actual sender (Constant Contact), some can be sent to the email address you selected as the “from” address for your campaign

What Is The “Other” Bounce Category?

As stated in a previous post, we sort our bounces based on information that the ISPs provide us.  If the information they send back isn’t clear, it may get sorted into the “Other” category. 


Should I Remove My “Other” Bounces?

That is a tough call. I recommend obtaining a secondary email address for the contact if possible. If the address continually bounces and you are confident that it is a valid contact, then please contact our Support Team to troubleshoot.


Where Can I Find These Bounces? 

If you look at the reporting for a specific campaign, click on the number of bounces you have.  Then select your choice from the “All types” drop down.




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