Sending from an alternative domain (thats not on miab)

I use miab and love it. I need to send email using a different sender address.

my miab has and has the domain in the dns
I want to be able to send email with “from” as (but I don’t host

I added an alias for to, so miab then added to the dns and allows me to send as

The problem with this solution is while I can email using From, if I want to email others that are on (which I dont host) like it won’t work because miab thinks is on my server

any ideas how to get around this ? so i can send as but also email other address at which is on another server

James would need to be setup to allow your server to send mail as It is a bit complex and not really designed for that.

found a solution… i removed aliases so there’s no name server entry, then added relay_domains = to the /etc/postfix/ file and restarted postfix

(as mentioned I’m not hosting so dont receive mail for it on my server)

just fyi… the reason for this is the is a microsoft exchange server which isnt set up for smtp authentication