Newbie questions re: hostnames, loopback, rspamd

NewCow

Hello All! I have Dockerized Mailcow running on a VPS. This is all new to me. I’ve been over all the config files, DNS and settings many times trying to get this working. I feel like I’m so close! I could use a little help to get over the last hill, please.

Should the hostname in mailcow.conf and data/conf/postfix.cf be the same as the MX record?

Why do I get:
"warning: host mail.domain.website[“insert my IP here”]:25 replied to HELO/EHLO with my own hostname mail.domain.website" and
"warning warning: host mail.domain.website[“insert my IP here”]:25 greeted me with my own hostname mail.domain.website"

I also get a log message about host looping back to itself so can’t send/receive message, but I can’t find it again…

And I get:
“warning: connect to Milter service inet:rspamd:9900: Connection refused”

I’ve solved so many problems on this journey I feel I could re-write the Mailcow documentation, but these last few I haven’t been able to crack. Any and all help will really be greatly appreciated!!! Thank you.

NewCow

Quick follow-up:

I can send fine, everything works; spf, dkim and dmarc. Mail is received at its destination with “clean” headers.

The loopback problem is with receiving. The message was not in a log, it was in a bounce back from an email I tried to send from another server to myself. Too tired/bleary eyed…

"MAIL…@…domain.website
2:33 PM (2 hours ago)
to me

This is the mail system at host mail.domain.website.

I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

               The mail system

me@domain.website: mail for domain.website loops back to myself"

luchris

Hi, usually i give a name to the box. Something like server1.domain.com and this will be the hostname. I will setup DNS and records for server1.domain.com, mail.domain.com etc. In mailcow, i use server1.domain.com, different from the user@domain.com to satisfy postfix configuration.

mailcow will setup certs for server1.domain.com. I will make mailcow setup another for mail.domains.com. Edit mailcoow.conf ADDITIONAL_SAN= mail.domain.com

With this cert, outlook will not prompt to use cert.

NewCow

First, thank you for the reply and assistance! This assumes a lot of knowledge I don’t have yet…

I name the box where? Linux host name, in place of localhost?
DNS I can do.
In mailcow you use the same as the box name so it shows up at the top of the login screen?
How is server1.domain.com different from user@domain.com? domain is different for each? domain1 & domain2?
I can edit mailcow.conf to add ADDITIONAL_SAN.
Not sure what Outlook has to do with it, I don’t use it.

Thanks again, for helping, I appreciate!

luchris

NewCow Hostname and make sure it resolves to your public IP. server1.* is a sub domain of domain.com so to satisfy postfix configuration. If you dont use outlook, maybe thunderbird? General email clients will prompt you to install the cert if the cert name and incoming/outgoing server name is different.

NewCow

So, mailcow could be mail.domain.tld and gets an MX DNS record. postfix could be server.domain.tld and gets an A DNS record and they both point to the same IP? Somehow I had the idea in my head that the two domains had to be different, but really just the hostnames need to be different…

I’m going off the grid for a few days. As soon as I get back I will make the changes and post the result here.

luchris

NewCow Yes that is absolutely correct.

NewCow

Well, I’m back on the grid. mailcow.conf has mail.domain.tld and postfix/extra.cf has server.domain.tld. Incoming mail still does not work. It gets bounced back and the error message is “mail for domain.tld loops back to myself”

I wish I could understand what the “path” of an email is within my computer.

A computer on the Internet (an MTA?) has an email to send to me. It queries DNS with domain.tld from the email and finds the MX record for the domain which tells it what IP address to send it to. It then connects to port 25 on my computer and does the HELO/EHELO handshake. What piece of software on my computer is conducting that; mailcow, postfix, postcow? It tells the other computer that it is mail.domain.tld. Then that piece of software tries to pass the message along within my computer. Whatever software its trying to pass it to must also have the name mail.domain.tld which is why there is a problem with the loopback. What piece of software is the second one to handle the email? That must be the one I have to change the name of, from mail.domain.tld to server.domain.tld?

Or should it all be the other way around? Should server.domain.tld accept the message first and then within my computer pass it to mail.domain.tld?

I seemingly have everything else working, including sending mail out (spf, dkim and dmarc and DNS). So frustrating to be so close…

Thank you again for all assistance!!

luchris

NewCow mailcow.conf and postfix/extra.cf both should be server.domain.tld with A record. In mailcow UI, create domain.tld which has A & MX record. Usually i create mail.domain.tld.

NewCow

I did as instructed in last post and then sent myself an email from another account, below is from the postfix log:

04/30/2023, 02:33:59 PM warning warning: host mail.domain.tld[xxx.xxx.xxx.xxx]:25 replied to HELO/EHLO with my own hostname server.domain.tld
04/30/2023, 02:33:59 PM warning warning: host mail.domain.tld[xxx.xxx.xxx.xxx]:25 greeted me with my own hostname server.domain.tld

04/30/2023, 02:56:08 PM info 35D96E0523: to=me@domain.tld, relay=mail.domain.tld[xxx.xxx.xxx.xxx]:25, delay=5.2, delays=5.2/0.03/0.02/0, dsn=5.4.6, status=bounced (mail for domain.tld loops back to myself)

luchris

NewCow mailcow.conf : MAILCOW_HOSTNAME=server.domain.tld postfix/extra.cf : myhostname = server.domain.tld

Restart mailcow. I use bind for my DNS.

SOA domain.tld
server IN A xxx.xxx.xxx.xxx
mail IN A xxx.xxx.xxx.xxx
IN MX 10 xxx.xxx.xxx.xxx
dmarc IN TXT “dmarcxxxxxxxxxxx”
IN TXT “spfxxxxxxxxxxxxx”
public.domainkey IN TXT “dkimxxxxxxxxx”

xxx.xxx.xxx.xxx = same external IP

NewCow

Everything seemed just perfect according to what you have listed. Was pulling out my hair. Finally, in desperation, I wiped the hard drive, reloaded Ubuntu and installed Mailcow from scratch. Bingo! Now working, I can send and receive email. No idea what the difference is. Now I will work in getting SSL, anti-virus and anti-spam going. Thanks again for all your help. I learned a lot in the process!

SSL now working, I’ve firewalled port 80. I can connect to Mailcow and SoGo on port 443.

NewCow

Hmmm, I turned port 80 back on, seems that Acme uses it. Anti-virus and anti-spam seem to be working. I believe I am 100% up and running! I ran every applicable test that MXToolBox offers and every one is all green! I looked through every log on the system and don’t see any problems. Whew!!

luchris

Good job! So long hostname and the MX is different, you wont get the loopback error.