Domain cannot match hostname (how add my FQDN?)

tuupt

Hello,
maybe I’m too noob?

How can I add my mailcow server domain “mail.example.org” to “Add domain”?
It says “Domain cannot match hostname”.

And I dont find a documentation about the Mailcow-Webinterface. Can you help?
Thank you

MAGIC

You may want to add only example.org as domain so you can create mailboxes which are named like example@example.org

tuupt

I misunderstood the dns domain configuration.
How the config needs to be, for two mail servers?
not.mailcow@mydomain.org (mail server by provider)
mailcow@mail.mydomain.org (mail server by mailcow)

Should that work?
; MX Records @ 60 IN MX 10 mail.mydomain.net. mydomain.net. IN MX 10 mx1.provider.de. mydomain.net. 3600 IN MX 20 mx3.provider.de. mydomain.net. 600 IN MX 10 mx2.provider.de.

But in Mailcow UI its not possible to add mail.mydomain.net as the mail domain.

EDIT: Cant delete the mailto link

tuupt

My questions is:
How can the MAILCOW_HOSTNAME at same time the mail domain?
E.g.:
MAILCOW_HOSTNAME=mail.example.com

When trying to add mail.example.com as domain, this error message apears: “Domain cannot match hostname”

How to configure Mailcow to have for use e.g.: mailcow@mail.mydomain.org
Thanks

rcd

Same question really.

Yes I understand that most would want @domain.com, but I would like to use @mail.domain.com.

What is the logic that the MX can not be the same as the hostname? That seems a rather arbitrary rule?

aaronsmith

Assuming when you say “Add Domain” we’re talking about within the mailcow’s admin UI?

If so, for this part you must only specify what’s on the right side of your intended email address. For example:

Mailcow Hostname: mail.example.com
Email Address: user@example.com

In this setup, you add “example.com” for the domain within the mailcow admin UI. You do not specify “mail.example.com” because that’s your fully-qualified hostname (FQHN.) Then you can setup mailboxes for that domain in the next tab.

The MX records are then setup as follows:

Mail Server: mail.example.com

You must also setup A (IPv4) or AAAA (IPv6) that maps “mail.example.com” to its IP address.

When all this correct, here’s what happens when another server wants to deliver an email message to your email address:

Looks up the MX record for “example.com”, gets a reply “mail.example.com”.

Looks up the A or AAAA record for “mail.example.com” to find out its IP address.

Connects on the respective port to your server to deliver the message.

–

@rcd Assuming you own “domain.com”, to have an email address of “user@mail.domain.com” means setting up a sub-domain under “domain.com” first using a CNAME record.

CNAME records are aliases, so CNAME “mail.domain.com” would be an alias to “domain.com”, then you can setup your MX and A/AAAA records for your mail server accordingly.

–

Additional notes: Make sure you setup the reverse DNS (rDNS) as well. You should be able to “name lookup” your mail.example.com hostname to get its IP and reverse lookup the IP to get the name.

Once you have all this setup and working, you’ll also need to setup 3 TXT records for your domain, otherwise your emails will quickly get marked as spam by other email systems:

SPF - https://www.cloudflare.com/learning/dns/dns-records/dns-spf-record/

DKIM - https://www.cloudflare.com/learning/dns/dns-records/dns-dkim-record/ … once you add your domain in the mailcow UI, it will generate a key for you to specify for this record

DMARC - https://www.cloudflare.com/learning/dns/dns-records/dns-dmarc-record/

rcd

@aaronsmith

I just realize the problem is probably that you can’t create a mail domain in mailcow with the same name as the underlying linux host. So if the server running docker running mailcow is called mail.mydomain.com I can’t create a mail domain with that name. I guess it could easily be fixed by giving the host another name, so probably no big deal, I just didn’t quite understand the error I got.

aaronsmith

Ah yes if your hostname is the same as the intended domain name, then you cannot do that. I believe this restriction has more to do with the SPF and DKIM checks typically required to work in order to ensure your email isn’t flagged as spam.

numnum

So, the question is still on: “How [to] add my FQDN?”

I have the same issue and I think a lot of others too.
What is the solution? Is there a workaround? Please advise!

DocFraggle

You could rename your server to ‘mx.mail.example.com’, then you would be able to use mail.example.com as your domain. It won’t work otherwise without changing the mailcow code which currently prevents this.