In a few days our Mail Hoster (IONOS Germany) intends to activate further restriction for mail submissions.
For all submitted mails the mail sender domain has to match the mail domain of the user who submits the mail, where "user" means the user name (email address) for authentication the mail submission attempt.

All of our 20 users submit their mails with personal sender addresses to MercuryS, and Mercury C is submitting all of them to the mail provider via the one and only MercuryC user credentials. But all personal email addresses have the same mail domain like the "submitting user" defined in MercuryC. Should work.

So far so good. But in case I've set some Mercury filters where certain incoming external mails will be directly forwarded to the internet again (bouncing), the sender address will not be replaced by a local mail address. And this will lead to a refuse of that mail submission.

Hello Joerg,

what is going on at your ISP???

I guess your best option would be to setup for each of your outside email addresses a seperate instance of Mercury, slick and just for the forwarding with MercuryC and the corresponding email authentication. This way you would have the same situation as for your main users.

It would look like: coming in as usual BUT forwarding to your inside extra Mercury (port seperated for each) and send it off as you do right now.

Johannes

Do you really want to manage maybe 10, 20 or more instances?

Maybe I didn't write it clearly enough. Sorry for the translation.
After consulting our ISP he confirms that all of our different personal email addresses will further be processed even when subitted by only one authenticated user, provided that the sender mail domains matches the mail domain of the submitting user (and which are all registered addresses with the ISP). So far so good.

But any mail bounces or direct forwarder, triggered by Mercury filters, will fail.