Q line

Q line

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The DSN ORCPT address

V8.7 and above

When a mail message arrives that includes an ORCPT parameter for the ESMTP RCPT command (see RFC1891), sendmail needs to save that parameter's information separately from the RCPT recipient address:

 RCPT TO:<[e-mail]> ORCPT=rfc822;[e-mail]    recipient address   parameter's information  

Not all sites understand DSN. If sendmail forwards the message to such a site, it needs to omit the ORCPT parameter. Consequently, sendmail must not store that parameter with the RCPT address.

The Q line is used to separately store the ORCPT parameter information:

 Q   type   ;   addr   

The type ; addr is defined by RFC1891. The sendmail program checks the syntax of addr when that information is received but otherwise merely stores type ; addr as is in the Q line.

There must be only a single Q line for each recipient R line, and each such Q line must precede its corresponding R line.