bounceHammer have been downloaded and used by many users and companies since the first release on March 2010 and has been EOL: End Of Life on February 29, 2016. Thanks for using bounceHammer for a long time. We are now providing Sisimai (the successor of bounceHammer, more faster, more higher precision of analysis) as a bounce mail parser library in BSD 2-Clause License.
There are many bounce reasons which found by bounceHammer. When you scrub email addresses of your website users or mail magazine subscribers, You should decide whether to send an email again to a recipient which is already bounced at previous delivery.
In this article, we show our interpretation of each bounce reason for sending an email again. Note that the percentage of each bounce reason is our sensuous value.
It is almost impossible to send an email again to a recipient
which is bounced by the following reasons.
You should exclude the recipient email address from your list to delivery.
A domain part (the right hand side of @ sign) is misspelled, a domain name does not exist, or a domain name has been expired. If the user registration program working on your website checks an email address insufficiently, bounces by this reason will be occurred frequently.
A local part (the left hand side of @ sign) is misspelled or a recipient's mailbox does not exist.
Several providers will reject SMTP connection from a host which is sending an email to unknown user continuously.
It is too difficult to send an email again to a recipient which is bounced by the following reasons.
An email bounce by this reason is rejected by the header content of an email you sent.
Mainly a recipient's mailbox exists but the recipient can not receive a email for any reason, or the recipient is rejecting an email, and so on.
If you seen a bounced email which is returned by this reason, your envelope sender address (SMTP MAIL FROM:) is rejected by the remote host.
This reason mean the following things:
Recipient's mailbox has moved and recipient's email address has changed.
But this bounce reason is not rarely seen. This reason means that recipient's email addres has changed but it is not forwarded automatically.
This bounce reason means that contents (include headers) of the email you sent violated remote host's security policy.
For example, an email contains any virus, a source host's IP address is found DNS-Based blackhole list. But when a connection simply rejected, an email will bounce by this reason.
Less frequency, some remote mail server returns an email with this reason as alternative of "User Unknown".
When you seen a bounced email with this reason, you should investigate the maillog carefully.
The following bounce reasons mean that a destination mailbox could not be received an email temporarily. There are many reasons of temporary failure, a retransmission may be successful if you send an email some time after.
This bounce raason means that a destination mailbox is full or exceeds the limit of the server.
If a bounced email often returns by this reason for long time, the destination mailbox has been neglected or no email is retrieved from the mailbox.
This bounce reason means that no response from a destination mail server or
a domain part of a recipient email address did not resolve.
A bounce message will returns like the following process:
This bounce reason also means the followings:
The following bounce reasons mean that an email bounce has been caused by a destination host (mail server), not a destination email address.
In many cases, the destination host could not receive any email temporarily. You may retransmit an email after several hours.
These bounce reasons mean that a destination mail host's disk is full.
The destination host can not receive any email any more. You may send an email again after several hours (after the administrator resolved disk full problem).
These bounce reasons mean that a destination mail host does not accept an email temporarily due to high load or under the maintenance. You may retransmit an email after several hours.
Meanwhile, there is a destination host which returns bounce email by these reasons for a long time, the host may not receive an email forever.
This bounce reason means that an error occurred for a mailer program bug on a destination host. The mailer program is a program which is called from MTA (such as aliases) like following:
If the mailer program exited on other than 0 or 75 (status code), a bounce message by this reason will return to a sender.
This bounce reason means that some system error occurred like a configuration error on a destination host.
The following bounce reasons caused by an email content or email format.
When email size is too big (such as a big attachment file) for a destination host, a bounce message with this reason will return to a sender.
If a destination mail server could not parse or convert an email you sent,
a bounce message with this reason will return to a sender.