bounceHammer has been EOL'ed on February 29, 2016

EOL on February 29, 2016

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.

Commercial Support

  • 1Setting Up Sisimai Your Server
  • 2Support developmenet using Sisimai
  • 3Support via Email
  • 4Support bounce management
  • 5Parsing your bounced emails

What is a bounced email ?


bounced email ?

A bounced email ( simply a bounce ) is a email message from mail server (MTA) informing the sender of another message about a delivery error. It is also called as a returned mail, an error email, and an undelivered mail.

More information about bounced email is described in

The email headers and the message body of bounced email



A bounced email is created by MTA ( Such as Sendmail, Postfix, and qmail ) automatically when delivery error occurred. Contents of the subject header of bounced email like followings.

  • Returned mail: see transcript for details
  • Mail System Error - Returned Mail
  • Non Delivery Notification
  • Undelivered Mail Returned to Sender
  • Postmaster notify: see transcript for details
  • Delivery Status Notification (Failure)
  • Warning: could not send message for past 4 hour
  • failure notice


A sender of bounced email is mainly postmaster or MAILER-DAEMON. You will find names like the followings in From: header of bounced email.

  • MAILER-DAEMON@hostname of mail server
  • Postmaster
  • Postmaster@hostname of mail server
  • Mail Delivery Subsystem
  • Mail Delivery System
  • Mail Administrator

Message body of a bounced email

A bounced email is created by mail server program such Sendmail, and contains delivery report in its message body.

bounceHammer reads a bounced email and parse its headers and its message body, then find details about why the delivery failed. The following section is particularly important to find details for bounceHammer.

  • Status: 5.1.1 <- Various error codes
  • Diagnostic-Code: ... <- Error message, response of SMTP server, and so on.

bounceHammer is a system which parses a bounced email, finds a reason of bounce, classifies a recipient (PC, Webmail, smartphone ). Visit What is bounceHammer ? page to read more information about bounceHammer.