Apparently-To:
When the message lacks a recipient sendmail
If the header of a mail message lacks recipient
information (lacks all of the To:
, Cc:
, and Bcc:
header lines),
sendmail adds an Apparently-To:
header
line and puts the recipient’s address from the
envelope into the field of that line. This behavior
is hardcoded into pre-V8.7
sendmail, but beginning with
V8.7, it can be tuned with the NoRecipientAction
option
(NoRecipientAction on page
1060).
The Apparently-To:
header name is not defined in RFC2822. It is added
by pre-V8.7 sendmail because
RFC2822 requires at least one
To:
or Cc:
header, and neither
is present.
RFC2821 specifically recommends against the use of the
Apparently-To:
header, so that header should
never be defined in the
configuration file.
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