Mail scenario

[mtx]

Hello community,

So let's begin with the scenario and what i would (if possible) to achieve.

I have a mail server A for domain a.com which is handled by qmail + courier and a second mail server B which runs postfix + dovecot + mysql for (sub)domain sub.a.com.

I want to forward (i'm not quite sure this is the right term) some of the email addresses from A to B because i can't run IMAP on A and i really need it for those addresses. Now is it possible to do this and if yes what should i look for?

I would also like to use B as MTA for those users but if i send an email for example from user1@sub.a.com to appear as if it was sent from user1@a.com (i guess this is called address rewrite ?).

thank you and a great day,
v