Thank you very much, Dave. This looks very interesting.
Ken
iRedmail, small reliable, scalable and most of all totally free!
Dave
-----Original Message-----
From: ProFox [mailto:[email protected]] On Behalf Of Ken Dibble
Sent: 16 June 2016 19:34
To: [email protected]
Subject: [NF] Linux SMTP/POP Servers?
We've been running an internal email system that is built into the
ClearOS operating system (a version of CentOS that functions as a
SAMBA 3 domain controller) for many years. Along with the ClearOS
SMTP/POP server, we've been running MailMan on the same machine to
provide an internal listserv capability. Unfortunately, I'm going to
have to discard ClearOS and go with a Windows AD domain server. I
want to preserve the internal email and listserve functionality, and
I want to run it on one of my new Linux Synology NAS clones.
There are a bazillion options for replacements and I don't have any
reliable basis on which to evaluate them.
Do any of you have recommendations for Linux SMTP/POP server
software that would be suitable for running an internal email system?
By "suitable for running an internal email system" I mean:
1. The system will not/cannot/must not communicate with, or be seen
from, the internet.
The ClearOS SMTP/POP server is configured to only accept, and send,
email within its own domain (though this may be achieved by tweaking
Linux ports rather than directly within the email server, given the
information provided in the next paragraph, I don't know). The host
machine is behind a NATing router that does not have any open ports
for email. I need an email server that can be configured in the same way.
Related to this, I would prefer the ability to configure how the
SMTP server responds to invalid input, including messages addressed
to the internet or to invalid internal addresses. The ClearOS server
tries to send these several times, at increasingly long intervals,
so that it takes 3 or more days to put out a bounce-back message,
and this configuration can't be changed. I would rather that
bounce-backs take place immediately.
2. Must provide all standard POP3 functionality (thank you, but I am
not looking for an explanation of why I should use IMAP instead),
including the ability to communicate with a fat Windows email client
that will sometimes tell it to retain email on the server for a period of time.
3. Free as in beer, preferably, but if not an option, then I would
be willing to pay a reasonable one-time license fee, not based on
the number of email accounts, for perpetual use. I am not willing to
pay for a "software as service" arrangement.
4. Because it is an internal server with no connection to the
internet, it does not have to have all of the high-paranoia-level
security features that an internet email server needs. I will cope
with it if it does not pemit plain text authentication, but plain
text authentication is perfectly adequate and completely safe for my purposes.
5. It doesn't have to have any built-in spam filtering.
The current CentOS SMTP/POP server has annoying spam filtering
features that are buggy and can't be turned off. For example, zip
file attachments (and sometimes docx and xlsx attachments, which are
just zip files) go missing, and it can choke on other unusual file
attachments. None of this nonsense is necessary and I would prefer
for nothing to be built-in that filters spam or messes with
attachments. If any such thing is built-in, it needs to be able to
be turned off, and stay off.
6. If it doesn't integrate true listserv capabilities (no fudging
with "aliases" or numerically-limited forwarding lists) like those
of MailMan, then it needs to be compatible with MailMan.
7. Traffic requirements: I don't know much about what sort of
resources a Linux SMTP/POP server requires. Currently we have about
120 email accounts, each with a 1 GB mailbox on the server, and the
NAS will accommodate that without even blinking. Conceivably someday
we could be looking at more like 250 accounts. To the extent to
which that affects speed/responsiveness, then that's a consideration.
8. Easy to set up and configure, and if not, then EXTREMELY well-
and reliably-documented.
9. <rant>Probably not an option, but, since I want an integrated
SMTP/POP server, then, for the sake of the Mother of All that is
Good, would it be too much to ask for an integrated validation
system in which, just for laughs, the SMTP server simply compares
the sender's address to the POP server's list of valid accounts for
that domain to determine whether or not to accept and relay an
incoming message, instead of performing bollocks-oriented "test
sends" back to the user that will fail if the user's inbox, the
state of which bears no rational relationship to the person's
authorization, ability, or need, to use the SMTP server to SEND
email, is full, and calling it "validation", which it is,
emphatically, NOT?</rant>
Thanks for all of your suggestions and the benefit of your experience.
Ken Dibble
www.stic-cil.org
[excessive quoting removed by server]
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