Exim appending hostname to fully qualified sender address

exim

I'm having a problem at the moment on a corporate e-mail server whereby Exim is appending its server hostname onto the end of the sender's e-mail address, despite that e-mail address already being fully qualified.

For example, a user sends an e-mail from:

the.sender@mycompany.co.uk

and Exim is changing this to:

"the.sender@mycompany.co.uk"@corp-2.mycompany.co.uk

This is no longer a valid e-mail address and as a result receiving mail servers usually reject the message because it can't verify the sender.

Exim config at: http://pastebin.com/4nS6T1Aw

Exim output from a dummy delivery (exim -bh) at: http://pastebin.com/UTXC8RuR

From the looks of it, something weird is going on with quotation marks and I think Exim's tripping itself up, but I'm scratching my head on this one and would appreciate any help!

Thanks

Best Answer

In the early days of email, the email address format was generally user@hostname. Frequently, the sender that was passed to a mail server was simply the username, and the mail server automatically appended its hostname to the supplied username.

Over the past 15 years, it's become much more common for a mail server to be configured to accept email for multiple domains (not just its hostname), which is typically called "virtual mail." When it comes to virtual mail, the mail server must figure out when the argument being passed is just a local username, or if it's a full email address. When it's not a full email address, you want Exim to append the hostname (or default domain you specify), but if it is an email address, you want to tell Exim not to append that hostname/domain.

I have this in my MAIL acl, which tells exim to "retain the sender domain" (which is a roundabout way of saying "the domain is supplied, leave it alone").

  accept  authenticated  = *
          control        = submission/sender_retain
          control        = dkim_disable_verify
          add_header     = X-Authenticated-Sender: ${sender_address}
          set acl_c_authenticated = 1

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The content of the Received: header is defined in Exim by the configuration option received_header_text. The default setting, from which you can see how your example is constructed, is:

received_header_text = Received: \
  ${if def:sender_rcvhost {from $sender_rcvhost\n\t}\
  {${if def:sender_ident \
  {from ${quote_local_part:$sender_ident} }}\
  ${if def:sender_helo_name {(helo=$sender_helo_name)\n\t}}}}\
  by $primary_hostname \
  ${if def:received_protocol {with $received_protocol}} \
  ${if def:tls_cipher {($tls_cipher)\n\t}}\
  (Exim $version_number)\n\t\
  ${if def:sender_address \
  {(envelope-from <$sender_address>)\n\t}}\
  id $message_exim_id\
  ${if def:received_for {\n\tfor $received_for}}

As for changing or remove the header. Beware some best practice advice lies ahead..

Are you sure that you want to remove this information? It's presence allows you to track abuse reports much more easily. The exposure of your internal IP addresses is actually of fairly limited risk.
Technically you can remove this first received header by using headers_remove but it's certainly not RFC friendly and there is a chance of creating mail loops.
If you must mask the information then you would be best to do so by modifying received_header_text. For maintainability and the principle of least surprise, even if the MTA isn't performing any other functions, you probably want to make your changes as specific as possible. This would involve putting some additional conditions in those if statements for facts that you know will always be true, such as whether the sender has authenticated themselves.

Centos – Exim Problem: Sender address rejected: need fully-qualified address

It looks like this is the address the server is trying to use to send mail: alleart@V100723TU7C41-1 and it's being rejected. You may need to specify a valid email address in your php.ini file, or request a change through your hosting provider.

Best Answer

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Centos – Exim Problem: Sender address rejected: need fully-qualified address

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