I have an alias like this,
and somebody sends a message addressed to both info and peter, then peter receives the message twice. When I used Sendmail it detected the same mail going to the same user twice and prevented it. How can I do the same with Postfix?
I need your help. Please help me.
Dear Mr. Rana,
This is a common problem on postfix. But I am not going to tell it as 'bug', this is a fetcher.
Some people will complain that Postfix sends duplicate messages. This happens whenever one message is mailed to multiple addresses that reach the same user. Examples of such scenarios are:
One message is sent to the user, and to an alias that lists the user. The user receives one copy of the mail directly, and one copy via the alias.
Some people will even argue that this is the "right" behavior. It is probably more a matter of expectation and of what one is used to.
This can be "fixed" only by making Postfix slower. In the above examples, Postfix would first have to completely expand all distribution lists before starting any delivery. By design, Postfix delivers mail to different destinations in parallel, and local delivery is no exception. This is why Postfix can be faster than sendmail.
If you want to "fixed" this problem, I will suggest you to stay in sendmail.