On Sat, Feb 11, 2017 at 01:55:26PM +0530, Nitin N wrote:
> Now, I have to migrate to a new server that is running FreeBSD 11. 
> I need to support 4 domains on this single server with each domain 
> having its own Trusted CA certified SSL digital certificate.
> 
> I can think of three ways to accomplish this and I am looking for 
> some guidance based on your knowledge/experience with Postfix.
> 
> Method 1]
> 
> Use virtual domains on a single Postfix instance and override 
> master.cf to take care of the individual SSL certificate for each 
> domain using a separate IP in each case. Based on my research, I 
> believe this could get complicated with Postscreen and other 
> milters enabled. So I am not too keen on going this path. Correct 
> me if I am wrong...

Postscreen (which, BTW, is *not* a milter) and submission do not play 
well together.  If you must accept submission on port 25, do so with 
a distinct IP address which isn't published as MX for any of your 
domains, and only accept authenticated users there.

If there's only one IP address and you cannot fix the problem of mail 
users submitting mail on port 25, you're probably going to have to 
disable postscreen.

Certificates only matter on submission, and there only if your user 
base is large and beyond your control, such as at an ISP or 
university.  Small-timers can just tell their users, "this is the TLS 
certificate we're using, accept it."

> Method 2]
> 
> Use postmulti and create a separate instance for each domain. In 
> this case, I am not sure how complex it might get if I want to 
> create further instances for each domain to handle outgoing, 
> incoming and null-client scenarios.

Why would you want to do this?  If you're seeking Perfect Headers, 
why?  Users mostly can't read nor understand headers.

> Method 3]
> 
> Use FreeBSD jails for each domain and a common jail for all the 
> spam/virus protection services and use a proxy + NAT on the main 
> host. This could also help me use postmulti in each jail in case I 
> need to have multiple instances based on functions.
> 
> So based on your experience/expertise, which method would you 
> recommend?

Method 4: use a single IP address for mail, tell users what name it 
is (no reason why that name has to be "in their domain"), tell them 
what certificate they need to accept in their MUAs.  Offer and accept 
AUTH only on port 587; accept mail exchange only on port 25.

Your question and stated 3 methods indicate you don't understand much 
about the place of TLS in SMTP.  Yes, a user sending mail through 
your server needs to check (and to trust) your certificate, but 
remote MTAs will usually not ask for it and do not care.

> Further, do you think I can stop using Postgrey as I also have 
> Postscreen enabled?

With after-220 tests enabled, postscreen will easily block anything 
postgrey might have blocked.  Also, greylisting, ISTM, is mostly 
defeated by spammers' current methods.  It's typical for zombies to 
go through their lists more than once.

> I look forward to your responses.
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