The mailing list for listmasters using Sympa

["Silvers, Tim" <address@concealed>]

Is sendmail running and listening on an open port, probably 25? Try running:

 

ss -tanp | grep smtp

 

Confirm the firewall is open, as well.

 

firewall-cmd --list-all | grep smtp

 

nc -zv mailserver.domain.com

 

Just as a starting point.

 

Tim

 

 

From: address@concealed <address@concealed> on behalf of VTR <address@concealed>
Date: Wednesday, May 24, 2023 at 2:21 PM
To: address@concealed <address@concealed>
Subject: [External] Re: [en@sympa] Beginner's Help

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I appreciate all the responses I’ve gotten…very nicely explained. I’ve made some headway but am again stuck on the mail routing.

 

Setup: AWS Amazon Linux 2 with Elastic Public IP, Sympa RPM, SQLite, Sendmail (I’d already installed it when this list said I shoulda used Postfix…doh!)

 

My domain in Sympa is listsrv.domain.com

My server name for Sympa is mailserv.domain.com

 

External DNS:

 

A Record: mailserv.domain.com points to x.x.x.x (public IP)

MX Record: listsrv.domain.com points to mailserv.domain.com

 

Ran a telnet session on my Sympa host and see this error in my Sendmail logs:

 

May 24 17:15:51 sympahost sendmail[3855]: 34OHDSuO003855: address@concealed, size=68, class=0, nrcpts=3, msgid=989788, proto=SMTP, daemon=MTA, relay=localhost [127.0.0.1]

May 24 17:15:51 sympahost sendmail[3859]: 34OHDSuO003855: address@concealed,address@concealed,address@concealed, delay=00:00:49, xdelay=00:00:00, mailer=esmtp, pri=180068, relay=mailsrv.domain.com. [x.x.x.x], dsn=4.0.0, stat=Deferred: Connection refused by mailsrv.domain.com.

 

Do I have the wrong records set up? Thoughts?

 

------

On May 23, 2023, at 3:22 PM, Stephen Jarjoura <address@concealed> wrote:

 

Your question was:

What value do I use for domain, since the primary is pointing to O365?

 

The answer is: a subdomain, such as «lists.example.com»; this is something you pick. BC chose «listserv.bc.edu», but that's for historical reasons. Choose what works for you.

 

Whatever you choose, will determine how the mailing lists are addressed. If you have a list named "support" and you choose a subdomain of «lists.example.com», then the list address becomes «address@concealed».

 

Then you have to publish a DNS entry so that mail addressed to «address@concealed» get's routed to your new Sympa host. There are several options depending on how your data center is run.

 

1) You can just set the hostname of the server hosting Sympa to the desired name, like "lists". If your domain is «example.com» and you've set the hostname for the Sympa server to "lists", then its FQDN becomes «lists.examples.com». As long as there is an A record for that published in DNS, you're all set.

 

2) If you can't change the hostname of the Sympa host to your desired subdomain, then you need an alias pointing the subdomain to the actual domain. For example, a CNAME.

CNAME «lists.example.com» points to «actual-sympa-host-name.example.com»

This can also be done with an MX record.

MX «lists.example.com» points to «actual-sympa-host-name.example.com»

 

3) If you can't set a CNAME because you're using something else to route the mail for you, then you have to use an MX record.

MX «lists.example.com» points to «mail-router.email-provider.net»

Of course, your email router would need to know to route inbound mail addressed to «lists.example.com» on to the correct host.

 

----

 Here is how Boston College is currently set-up:

• Our primary domain is «bc.edu», and our MX record points that domain to Google's mail servers (similar to how you have yours pointed to Outlook.com).
• We've chosen the FQDN for our mailing list server to be «listserv.bc.edu», this is not the actual name of our server.
• Our internal DNS uses two (2) A records, one is «listserv.bc.edu», the other is «actual-sympa-host-name.bc.edu», and they both point to the same IP address.
• Our external DNS has an MX record for «listserv.bc.edu», which points it to the anti-virus/anti-spam mail router we use; in our case, that's ProofPoint.
• We've configured our mail router (i.e. ProofPoint) to accept mail on behalf of «listserv.bc.edu», scan it, and then forward it on to the actual server hosting Sympa.

Notice, we didn't actually mess with our primary mail route or MX record, at all. It's all separate: separate DNS records, separate mail routing paths, separate destinations.

 

----

While method #1 is the easiest, you probably can't do that in a large data center with strict naming rules. Method #2 has several advantages, like being able to "re-point" the subdomain to a different host, when needed.

 

Consider:

• Your current Sympa host is named «sympa-host-01.example.com»
• You need to update Sympa or the operating system or both, but don't want a lot of down time
• You build and prep «sympa-host-02.example.com» while still running 01
• When it's time to cut-over between the two hosts, you would:

• shutdown Sympa on host 01 and host 02
• Sync DB, list directories, and archives from 01 to 02
• Update the CNAME so that it points to host 02
• Start Sympa on host 02

• None of your list addresses will need to change, nor will your users need to change anything about the way they're using the server.

Anyway, I hope this helps a little.

 

-- 

Stephen A. Jarjoura

Collaborative Services

 

 

On Tue, May 23, 2023 at 11:36 AM VTR <address@concealed> wrote:

Thank you for the response. But I’m confused...

 

Our current MX is:

Host Name Mail Host

example.org example-org.mail.protection.outlook.com

 

I can’t change this since it points to M365 for routing.

 

And what is sympa-host.example.com? The public IP address of my Sympa server?

 

------

On May 23, 2023, at 11:20 AM, Stephen Jarjoura <address@concealed> wrote:

 

We created a subdomain for our Sympa instance, and it gets its own MX record.

 

MX example.com mail.example.com

MX lists.example.com sympa-host.example.com

 

Then you need to configure sendmail to receive and send as domain name you chose for your Sympa host, i.e. "lists.example.com".

-- 

Stephen A. Jarjoura

(e) address@concealed

Collaborative Systems Group

Information Technology Services

Boston College

 

 

On Tue, May 23, 2023 at 11:10 AM VTR <address@concealed> wrote:

I confess, I am weak on Linux and mail routing and but have been tasked with setting up Sympa for my company.

 

We have an Office 365 tenant with MX pointing to it. Let’s call the domain example.org. All mail gets delivered to it.

 

My company wants to set up a Sympa server for mail list management.

 

I installed Sympa on a variation of RHEL, installed SQLite, installed Sendmail, and am stuck here.

 

What value do I use for domain, since the primary is pointing to O365?

 

Do I set up a subdomain, like mail.example.org, and, if so, what DNS records do I need?

 

Sorry for newbie questions!

 

Thanks!