Importing Mails without "to" header

[Larry Rosenbaum]

> > This is valid:         To: undisclosed recipients :;
> > This is not:           To: <undisclosed recipients>
> >
> 
> I would say that the former is not actually valid, though the syntax looks
> correct. RFC2822 section 3.6.3 says that To:, Cc: and Bcc: must contain at
> least one address.

Not exactly.  Bcc: can be empty (note that the syntax line in 3.6.3 is
slightly different; it allows either address-list or CFWS).  Also, To: and
Cc: must contain an "address-list", but this requirement can be satisfied by
an empty group construct, as in the first example above. (In a group
construct, the "mailbox-list" is optional.)

>  None of the three is
> required, so if there is to be no recipient address in the header, the
> To: and
> Cc: lines should be absent.  (If I remember correctly, RFC822 did
> require
> either To: or Cc: to be present.)

It requires either To:, Cc:, or Bcc: to be present.  If there is no
recipient in the header, the message can have either an empty Bcc: or a To:
with an empty group construct.  I don't think this changed with RFC2822, but
I can't find anything in the document that indicates that a destination
field is required.