Analyzing Email Failures

Bounces & Repeat Bounces

A bounce occurs when a sent message is rejected by the receiving mail server. The most common causes for bounced email messages include a misspelled email address, a nonexistent email address, or a full recipient inbox. 

A repeat bounce is when an address has bounced, then bounced a second time and logged to the Bounce List, but then it is manually sent again. Our system does not attempt to deliver the message, because the system ‘knows’ that address is bad. This shows up on the Email Activity tab as a drop with the reason “bounced address”, and as a “repeat bounce” on the Statistics tab.

Hard Bounce

This type of bounce occurs when the receiving server returns a 500-class error, communicating no additional attempts to deliver to that server or email address are needed. A common reason for a hard bounce is “no mailbox for user”,"invalid alias".

Spam reports & repeat spam reports

If a recipient of your email feels that they received it in error, or simply did not wish to get the email from you, they may click the “report spam” or “junk” button. Spam reports can negatively affect your reputation and deliverability, so it is very important to make sure you send to people who really want your messages. We recommend to always include a clear, easy way to opt out of future messages from your organization, by way of a subscription management link. Finally, a clear and fair initial opt-in process will mitigate potential spam reports down the road. Repeat Spam reports are the number of messages that were sent to addresses that had reported mail as spam, and were therefore dropped. Think of the number more as “number of emails suppressed because the address reported email as spam”.

Invalid email

An invalid email occurs when you attempt to send to an email address that is formatted in a manner that does not meet internet email format standards. Examples include addresses without the “@” sign, addresses that include certain special characters, or spaces in an address. This response comes from our own server, since an invalid email is impossible to even attempt to send to its [non-existent] destination.


In certain cases, Guestfolio will “Drop” a message to a specific email address in order to protect your sender reputation. Guestfolio keeps Email Lists to track bounces, spam reports, and unsubscribes for each of our users. If a user sends a message to an email address that exists on one of these lists within their account, Guestfolio will automatically drop the message (i.e., not send to the address).