What are bounces?

When analyzing your newsletterdelivery statistics, you may have spotted the item “Bounce,” “Error messages,” i.e., emails not received, and you may have wondered why some communications did not reach the recipients, and by Googling you may have found information on what bounces are.
Bouncesare those emails that, although sent, are blocked by the receiving server and not delivered to the recipient.

The percentage of messages that come back because their delivery is impossible is the bounce rate and is an important indicator of the quality of the list.


Hard and soft bounce

Depending on the type of error, we distinguish bounces into hard and soft.

Hard bounces: are permanent errors that typically occur if emails are sent to non-existent or no longer used (and consequently, disabled) recipients

Soft bounces: are temporary errors that occur, for example, if the receiving server momentarily has reception problems or the mailbox is full and cannot receive further messages.
In this case, forwarding is attempted several times until, if there is no positive response, the bounce is classified as hard and handled as such.

How are bounces handled on Infomail?

When uploading a list, Infomail identifies any formally incorrect addresses (e.g., lack of @ symbol, space between letters, absence of domain) and automatically discards them.
This is already a great way to avoid sending communications to incorrect recipients.

On the first submission, however, it will be possible to check for addresses that, although formally correct, are in fact incorrect.
For example, the address “mario.bianchi@gmail.c” will be discarded by Infomail because it lacks the “.com” top-level domain, while the email “” is loaded correctly into the list despite not existing.

The first time you send to the box it will be bounced.
This will remain within the list but the status will change from active to inactive(visible by the ban symbol); all future sendings to the list, will then be made only to active email addresses, while deactivated ones will be excluded, and obviously will not be counted in the credits consumed.

In the Report section you can see the sending statistics and bounce rate.



In order to get information on the exact type of error, click on the button in the upper right corner “Download details as CSV,” download the Excel file, and analyze the column under “Error Message” in the report.




How to analyze bounce error codes

The receiving server’s response is provided by a numeric code with a short description.
The most frequent error code is 550, which indicates an inability to reach the recipient’s mailbox.

The error message in the image above indicates that the recipient’s mailbox is full, so the mail client has rejected the message.

Here are more examples of mail client responses:

‘smtp; 550-5.1.1 The email account that you tried to reach doesnot exist. Please try 550-5.1.1 double-checking the recipient”s email’ (email doesn’t exist)

‘smtp; 550 5.1.1 <m******@*******> : sorry, nomailbox here by that name (#5.1.1 – chkuser)’ (email doesn’t exist)

‘smtp; 550 Requested action not taken: mailbox unavailable’ (email doesn’t exist)

‘smtp; 550 Invalid Recipient [smtp-19.iol.local; LIB_520]’ (email doesn’t exist)

As you see, although the error code is the same, the description may vary from server to server.
It may also happen that the reported message is incorrect such as the case where a box that is actually no longer used and disabled is indicated as full.


Do you want to put these directions into practice?

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Exclusion of bounced boxes

Excluding bounces from all postings after the first one will save you some work, and you will get a great credit savings!
For this reason, in case you need to re-load an already used list, we recommend removing all non-existent addresses first.

After each mailing download the statistics and check the types of bounceerrors, go to the list on Infomail and delete the boxes with this type of error.


The case of unsubscribed email accounts is different.

Unsubscribed addresses will no longer appear in the list and cannot be re-entered directly.
Find unsubscribed emails in the Lists section by clicking on the button in the upper right corner.

If a user has unsubscribed by mistake you can reactivate them from within the Blocked Contacts List and re-enter the box in the list.



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