Mail sent to simply user instead of user@domain.com will have an X-Envelope-To: address of a simple user name rather then a full SMTP address.  This happens in a number of ways but most common is through the use of MercuryD and delivering using a user name in the MercuryD setup.  I do not know how you are setup but you must not be delivering via an alias, filter, MercuryD, etc using a simple user name or the forwarding will fail.

Hello

i try to forward mails via file but get allways errors, because the sender's address is not a fully quallified address, but the username of the local user.
504 5.5.2 <user001>: Sender address rejected: need fully-qualified address
where can change the sender's address to a fully quallified address ??

when i try to use the autoreply via file the sender is not a fully quallified address too - but this mail will be transmitted and delivered to an external address.
the sender is "MAILER-DAEMON" - where can i change this ?

thx

Make sure you are delivering using a full SMTP email address and not the simple username.  This may require you to use an alias if receiving mail via MercuryD.

ok, but where can i check using a full SMTP address - in the "Manage local user"-tab i cannot use an address as a username ?

[quote user="factorx"]ok, but where can i check using a full SMTP address - in the "Manage local user"-tab i cannot use an address as a username ?
[/quote]

You cannot check anything to do this.  This means that you cannot user the simple user name for delivery in MercuryD, filtering, aliasing, etc.  If you have a local PMail setup this also means you cannot use the simple local user name and need to send all mail via Mercury/32.

i don't use pmail, i have set up mercury as smtp and pop server.
now i put a FORWARD file in the folder of the postbox of an user.
what else have i to configure to get the forwarded mail sent with a fully qualified address and where can i do this ?
in the forward file i cannot place the senders address.