Sendmail relays incoming instead of putting it into user mailbox

[motiv8d]

I have a Redhat 6.2 server with ADSL, fetchmail and sendmail. I also have a domain name, which directs (catchall) any email to my bigpond email from which I download it to the server with fetchmail. eg: someone sends email to joebloggs@mydomain.net.au; it will be relayed to my bigpond email account myemail@bigpond.net.au; Fetchmail will then fetch it for sendmail.
The problem occurs in that fetchmail retrieves it, it goes to sendmail, however, does not go to a user mailbox on my system, rather sendmail will try to relay it back to myemail@bigpond.net.au - Then there is a never ending loop of relays from my sendmail server to myemail@bigpond.net.au and back!
My internal domain is set at the domain name eg: mydomain.net.au (real name is used, this is just to illustrate). If I send an email internally to say joebloggs@mydomain.net.au it arrives internally no probs.
If I look at the header of a mail item on the bigpond email it will have
From: sender@sendersdomain.com
For: myemail@bigpond.net.au
To: joebloggs@mydomain.net.au
It seems that fetchmail/sendmail/procmail or whatever is ignoring the To: and just relaying to the For: address.
I cannot find a .forward or a .promailrc file either. Dont know if they should be there or not.
If anyone can tell me what is need to get the server to accept the To: address and not relay it to the For it would be greatly appreciated. Thanks in advance.

 

[trabadam]

The problem may be that sendmail by default applies address mapping read from /etc/mail/aliases.db or ~/.forward only to messages that are passed to local mailer. Sendmail thinks that mail for user@bigpond.net.au must be send to bigpond.net.au and passes that message to smtp mailer, which does not perform aliases & .forward lookup. This behaviour is controlled by "A" flag in mailer definition - if you look at sendmail.cf, you can see, that Mlocal statement has "A" among flags (set by F=...), while M*smtp* don't. Add "A" there, add string

myemail@bigpond.net.au: <my_login_name>@localhost

compile the DB by

# newaliases

and restart sendmail.
Notes:
The loop is not &quot;never-ending&quot; since max hop-count exists (which is usually = 16)
If your sendmail can talk directly to MTA at bigpond.net.au, it may be that none of them looks at &quot;To:&quot; field: the remote MTA makes decision based on &quot;RCPT TO:&quot; SMTP command, not the recipient address specified in the header.
.forward usually lives in the recipient's home directory, if it is not found there - just create it! Also you can look at &quot;O ForwardPath=&quot; statement in your sendmail.cf, see /usr/share/doc/sendmail/op.me about the meaning of all those $z and $w...