avoiding mail loops in fetchmail

[Paul Howarth]

Ankush Grover wrote:
> On 4/11/05, Paul Howarth <paul at city-fan.org> wrote:
> 
>>Ankush Grover wrote:
>>
>>>My fetchmail configuration file
>>>poll mailserver  localdomains domainname
>>>user " "  with pass " " to * here flush
>>>
>>>I am having catchall mailbox (multidrop mailbox) what happens is that
>>>when there is mails for 2 or more users in the catchall box the mail
>>>recieved by the user is 2 or more means if there are 4 mails then each
>>>user will get 4 mails .I want to avoid mail loops.I have posted my
>>>fetchmailrc above .Please have a look at it and tell me how to avoid
>>>loops.
>>>
>>>I am using catchall for many users in my office and so I want to send
>>>the mails from the catchall mailbox to the respective users.
>>
>>How does fetchmail know who to deliver the mail to?
>>
>>Are you aware of the well-known issues regarding using multidrop
>>mailboxes like this with fetchmail (see the fetchmail man page)?
>>Basically, unless your MTA adds a suitable header (e.g. Delivered-To:)
>>to indicate the actual recipient of the email, or there is one already
>>there (e.g. a To: or Cc: header), it won't work.
>>
> 
> 
> the mail is going to proper user it the mail is To/CC but not bcc.The
> exact problem I am having is that the mails even send to To/Cc are
> going to all the users.Suppor there is a single mail going to john and
> marry then john and marry will receive 2 copies of that mail whereas
> they should receive only 1 mail each.
> 
> Is there any other utility or program  through which i can download
> the mails for users from the catchall mailbox without any issues or
> problems.

No. The underlying problem is that once the mail has been delivered to 
your POP/IMAP mailbox then (unless your MTA adds a Delivered-To: or 
equivalent header) the envelope recipient address is no longer 
available, and fetchmail or any other utility (e.g. getmail) has to 
figure out who the intended recipient was based on the mail headers. For 
Bcc'ed mail, this information simply isn't there. So it won't work. Period.

This is described in detail in "THE USE AND ABUSE OF MULTIDROP 
MAILBOXES" in "man fetchmail".

Paul.