Until this time our company had a groupmail (all our mails comes to a global mailbox) at our ISP, and we used fetchmail with POP3 and multidrop mailbox setup to get all our mails and it is sorted and delivered to the local users by our internal mail server (by the help of the envelope option set to “Envelope-To”) . Mails are sent out by a smarthost.
This groupmail service solution will be terminated by our ISP.
My question: Can I setup mail-in-a-box to replace my ISPs groupmail?
I mean I would like to keep the in-house mail server as the main mail server, and setup a cathcall account in miab, and set the “Envelope-to” or “Original-To” or “Delivered-to” header to the original address, and get and filter mails by fetchmail as before, or is there a better solution to this problem?
You should not be letting all users send from the same email. That will cause legal issues down the road. I would setup MIAB and give EACH user their own mailbox, but configure forwarding rules in MIAB to forward their email to a “catch-all” account instead. That way you can be sure (legally speaking of course) that the user sending as username@example.com is in fact that user.
(I am not a lawyer, and this is NOT legal advice.)
I have run into this issue in the past. But even when not bringing legalities into the mix, giving each user their own mailbox will be MUCH faster experience for them, as well as an easier point to troubleshoot and maintain in the long run. With MIAB you will no longer need your ISP to deliver email.
Multidrop email is not about letting everybody to use the same email. This is a kind of intermediate queue between the world and our server (where all the sorting is done).