bounceHammer has been EOL'ed on February 29, 2016

Send an email again to the recipient

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.

Unknown Host(hostunknown)

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.

Unknown User(userunknown)

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.

Rejected by filter(filtered)

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.

Sender address rejected(rejected)

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:

• A remote host considers you as a spammer
• A domain part of envelope sender address was not resolved with DNS

Mailbox has moved(hasmoved)

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.

Security error(securityerr)

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.

Alternative of "Unknown User" (userunknown)

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.

Mailbox is full(mailboxfull)

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.

Delivery time expired(expired)

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:

• Send an email
• Cannot connect to the destination host
• Trying to connect or delivery several times for several hours
• Give up, your mta returns a bounce message to the sender

Problems on DNS or network

This bounce reason also means the followings:

• Your DNS server does not work properly
• Your gateway IP address is rejected or ignored by remote firewall

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.

Exceed limit (exceedlimit), Disk full (systemfull)

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).

Destination host does not accept an email(notaccept), Stopping temprarily (suspend)

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.

Unknown mailer error (mailererror)

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.

System error (systemerror)

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.

Message too big (mesgtoobig)

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.

Mail content error(contenterr)

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.