My POP3 server doesn’t receive email

email-serverpop3windows-server-2008

I'm using hMailServer 5.3.3, with only POP3 and POP3S protocols enabled.
I can telnet to the server just fine, but I can't seem to receive emails from anywhere (gmail, outlook)

I don't get any Mail Delivery msgs when sending, nor does the server log any connections trying to be made. The ports (110 and 995) are open (I've checked on online port scanner).

When I run the server's diagnostics tool, it prints the following:

Test: Collect server details hMailServer version: hMailServer
5.3.3-B1879 Database type: MSSQL

Test: Test IPv6 IPv6 support is available in operating system.

Test: Test outbound port SMTP relayer is in use. Trying to connect to
host … Trying to connect to TCP/IP address Trying to connect to
TCP/IP address on port 25.

ERROR: It was not possible to connect.

Test: Test MX records Trying to resolve MX records for …

ERROR: MX records for domain could not be resolved

Test: Test local connect Connecting to TCP/IP address in MX records
for local domain domain … ERROR: MX records for
local domain could not be resolved

If I enable the SMTP server, the diagnostic prints the same thing.

NOTE: I don't have a MX record set. Do I need it?

NOTE: When I try to send an email from a different local server (POP3+SMTP) to my gmail account, the gmail account doesn't receive the mail.

Best Answer

It sounds like you are expecting the POP3 server to receive emails from other providers (eg gmail). POP3 does not 'receive' email. POP3 is purely used for clients (eg Outlook) to connect to a mail server and pick up email stored in a mailbox. Email is delivered from sender to destination entirely using SMTP.

Email works as follows (ignoring stuff like Exchange which has different methods for moving email about internally that we don't really need to know about at this point):

  • End user sends you an email which gets delivered to their ISP via SMTP
  • ISP's SMTP server looks up your MX records and delivers the email, still via SMTP, to your mail server.
  • Your SMTP server receives the email and stores it in your mailbox
  • Your email client picks up the message from your mailbox using POP3/IMAP/etc.

I've never used hMailServer but you'll need to set it up as follows if you want it to handle email for your domain.

  • Enable the SMTP service and make sure it's working (should listen on port 25)
  • Configure hMailServer to handle email for your domain and set up your email addresses/accounts
  • Point the MX record for your domain at your mail server
  • Enable the POP3 service so you can pick up your emails
  • Configure your mail client to connect to hMailServer using the POP3 login details
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