How can I query postfix to test is an address is in the virtual address file?

Solution 1:

sendmail -bv [email protected]

Despite the name, this is a Postfix program. This will deliver an email to the caller's mail account that will give you the information about full address resolution. The command-line output is typically just:

Mail Delivery Status Report will be mailed to <yourusername>.

postalias -q will show you what the alias file has in it, as the previous responder said, but this may or may not be what actually happens; sendmail -bv is more complete.

Solution 2:

How about postalias:

 postalias -q [email protected] /path/to/your/valias_file