17 Feb
2023
17 Feb
'23
6:27 p.m.
Hello Murrey,
Yep, I've done exactly this back in a previous life, where I was working
as the networking odd-bod at a men's fashion retailer (please note that
it doesn't mean I have fashion sense). We had a proprietary mail
"firewall" at some point, which one day simply stopped working (I later
found out that it was because we stopped paying for the service and the
IT department, meaning me, was not informed). We had to put something in
place pretty sharpish, and in the end we settled on a combination of
Postfix and MailScanner. My chewing-gum and wet string solution served
the company until well after I left.
You will have a wide choice of things to use that would probably be
better than the above combination, but Postfix (combined with Dovecot)
as the hub of your solution will do you proud. I currently use a
combination of Postfix/Dovecot with amavisd-new to do content scanning,
and PostGrey with spamd (SpamAssassin) to weed out the weirdness and
rich widows from all over the world. It's not perfect, and it's
definitely due for a redesign. Even so, it works well enough so that I
rarely get something that defeats the system. I cannot remember getting
virus messages for well over 10 years, and only a very few spammy bits
make it through. To illustrate how high the rejected vs. received number
is on my creaky setup, here is a snippet from my Postfix log summary as
created by the pflogsumm tool:
---start---
Postfix log summaries for Feb 13
Grand Totals
------------
messages
135 received
145 delivered
1 forwarded
20 deferred (364 deferrals)
6 bounced
102 rejected (41%)
200 reject warnings
0 held
0 discarded (0%)
6726k bytes received
7469k bytes delivered
38 senders
30 sending hosts/domains
13 recipients
3 recipient hosts/domains
Per-Hour Traffic Summary
------------------------
time received delivered deferred bounced rejected
--------------------------------------------------------------------
0000-0100 6 6 28 0 17
0100-0200 0 0 14 0 0
0200-0300 0 0 14 0 0
0300-0400 4 2 2 2 7
0400-0500 4 4 20 0 6
0500-0600 0 0 16 0 2
0600-0700 5 5 16 0 8
0700-0800 2 2 14 0 6
0800-0900 0 0 14 0 2
0900-1000 12 10 16 2 19
1000-1100 5 5 6 0 11
1100-1200 4 4 16 0 13
1200-1300 2 2 32 0 5
1300-1400 6 8 16 0 17
1400-1500 14 16 0 0 28
1500-1600 12 14 16 0 22
1600-1700 8 8 16 0 17
1700-1800 18 22 16 0 42
1800-1900 4 4 16 0 6
1900-2000 16 18 16 0 28
2000-2100 0 0 16 0 2
2100-2200 4 2 8 2 13
2200-2300 4 8 18 0 14
2300-2400 5 5 18 0 17
---end---
I hope this whets your appetite for some mail server nerdery.
Cheerio!
Jan Henkins
On 17/02/2023 13:27, Murray Crane via BitFolk Users wrote:
Hello all,
Would any of you know if the following scenario is "doable"?
We run an old Exchange 2010 infrastructure at my work, and there is no
way they are going to spring for newer: getting them to go from 2003
to 2010 was an ordeal...
Could I set up an Ubuntu Postfix "relay" server between Exchange and
the Internet, that also permits one particular mailbox to be
accessible from a Dovecot install on the same server (as well as
relaying the mail for that mailbox to Exchange)?
Yes/no and pointers most welcomed.
Kind regards
Murray Crane
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