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Originally I was using one server (server A) which handled the web serving and email serving. This all was working fine.

Yesterday I wanted to take the web serving load off of the first server (server A) and put it on a new server (server B). This means that server A is now just an email server.

I have since tried to edit my DNS settings, and whilst the emails do work on SMTP, they seem to be failing on POP. I can send emails from the mail server (server A) but I can't receive anything anymore.

Attached below is a photo of my DNS settings.

Any suggestions would be useful. EG: Perhaps I also need to change something also in MailEnable? I mean, I shouldn't because all I've changed is the DNS settings to make the web traffic point to the new web server (server B).

Example of my DNS Here

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    You server is receiving/sending mails but your clients can't read them is this your problem? – Soulimane Mammar Mar 11 at 6:16
  • Other way around. I can send emails and they can receive them, but I can't receive emails from them. – t0rxe Mar 11 at 6:17
  • didn't get it! when you say I, you mean you can send email from the server ?? – Soulimane Mammar Mar 11 at 6:27
  • Yes, I can send mail from my server and it works. I just can not receive emails. – t0rxe Mar 11 at 6:36
  • Are your clients sending emails via webmail client or dektop client like outlook? – Soulimane Mammar Mar 11 at 7:46
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You don't have a MX record on the root of your domain (i.e. no record with Type MX and Name @), so any emails inbound to any.name@your.domain will fallback to the server indicated by the A record at the root of your domain, which now points to your server B. No wonder you are not receiving email!

So the problem is not with POP access between the email client and server A; it's that incoming emails from the world are not directed to server A in the first place.

The MX record with Name smtp would only apply to emails sent to any.name@smtp.your.domain, so it's probably a red herring.

You need the A record of the @ to point to server B, but the MX record of the @ to server A. HTTP access is directed by the A records only; it will completely ignore any MX records.

An email delivery, on the other hand, will first look on the MX records: it only falls back to directly using A records if an applicable MX record doesn't exist. A MX record will indirectly use the A records by specifying the name of the A record to look up for email delivery purposes.

You'll need to create the following MX record:

  • Name: @
  • Type: MX
  • Value: smtp.your.domain (i.e. the fully-qualified domain name of your server A), and priority 10

(The priority value is not very important when you have just one email server, but setting it to 10 allow you to easily add a new record with either higher or lower priority in the future, if it ever becomes necessary.)

Wait for an hour for the old DNS data to expire, and then your incoming email should work again. You might even get all the mail that was left undelivered after you made your DNS change, within a day or so.

  • So even though I have the MX records name as 'smtp' and that points to an A record, it won't work? It must be '@'?? That means that @ will point to server B though, won't it??? – t0rxe Mar 11 at 9:32
  • You need the A record of the @ to point to server B, but the MX record of the @ to server A. The HTTP access is directed by the A records only; it will completely ignore any MX records. An email delivery will first look on the MX records: it only falls back to directly using A records if an applicable MX record doesn't exist. A MX record will indirectly use the A records by specifying the name of the A record to look up. – telcoM Mar 11 at 9:45
  • Ah! That makes sense and it seems to be working again now too!! Excellent. Thanks for that fantastic explanation. There are some issues still outstanding however, such as - MX ERROR | No DMARC Record found. <br/> - DMARC ERROR | DNS Record not found. - HTTP ERROR | The remote server returned a (500) Internal Server Error. - MX WARNING | DMARC Quarantine/Reject policy not enabled. - DNS WARNING | SOA Expire Value out of recommended range. - SMTP WARNING | Reverse DNS does not match SMTP Banner. – t0rxe Mar 11 at 9:48
  • Welcome to email server administration in the 21st century. Your email server should also have a reverse DNS entry (a PTR record) that matches the fully-qualified domain name of the server, and also the name the server uses in its SNMP response to introduce itself to other mail servers. You also seem to already have a SPF record, but no DMARC records to go with it. By the way, what exactly is reporting those errors? – telcoM Mar 11 at 9:55
  • Hmm, I'll have to have a look into it more. The site reporting it was MX Toolbox – t0rxe Mar 11 at 10:00

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