Problems with $mydomain entries in virtual

I must be doing something wrong ... because it looks like to me that
putting email aliases for $mydomain in /etc/postfix/virtual can break
delivery to local users.

Detail
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I have just switched from sendmail to postfix.

I have encountered a problem with having @mydomain entries in the virtual
table. As a result, some users lost email. Either I did something wrong
(probably), and/or this should be clarified so that others don't get
bitten.

I have several domains, with a few users that have local unix mail
accounts. Therefore, I followed the instructions in
http://www.postfix.org/VIRTUAL_READM...#virtual_alias

However, I wanted to do some additional aliasing of my.domain, so I put
them in /etc/postfix/virtual:

michael@mydomain.com mth
miguel@mydomain.com mth

@mydomain.com bitbucket # defined in aliases as /dev/null

jane@otherdomain.com jane
sally@otherdomain.com sally123@hotmail.com


Mail is sent to jane@otherdomain.com
The mail log indicates that messages addressed to the local user jane get
mapped to jane@mydomain.com

Since jane@mydomain.com does not explicitly exist in the virtual file her
message gets routed to the bitbucket :-(

If I remove my 'mydomain' entries from the virtual file then jane's
message gets delivered locally.

Q: If I use the command line to send mail to 'jane' the maillog indicates
that it is mapped to 'jane@mydomain.com' ... Is this correct behavior or
is this a configuration error on my part?

In sendmail I put mydomain aliases + otherdomain aliases in the
virtusertable, with as little as possible in /etc/aliases.

Q: Did I do something fundamentally wrong by mixing mydomain + otherdomai=
n
in the virtual table?

Q: What is the right way to handle what I want to do?


Thanks for your time and assistance,

Michael