1 Topic by richardw

  • richardw
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  • Registered: 2018-11-07
  • Posts: 19

Topic: port 53 (DNS)

iRedMail 0.9.8
Ubuntu 18.04
MySQL
NGINX
iRedAdmin

Do I need port 53 open to query DNS in order to send/receive email?
from ufw status:
143                        ALLOW       Anywhere                 
25                         ALLOW       Anywhere                 
587                        ALLOW       Anywhere                 
53                         ALLOW       Anywhere                 
443                        ALLOW       Anywhere

from netstat -tlnp | grep :53
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      66449/systemd-resol

from netcat -zv mydomain.com 53
netcat: connect to mydomain.com port 53 (tcp) failed: Connection refused

I can neither send nor receive email from myuser@mydomain.com

Any hints?

Thanks in advance!

----

Spider Email Archiver: On-Premises, lightweight email archiving software developed by iRedMail team. Supports Amazon S3 compatible storage and custom branding.

2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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  • Registered: 2009-05-06
  • Posts: 30,788

Re: port 53 (DNS)

richardw wrote:

Do I need port 53 open to query DNS in order to send/receive email?

- For outgoing, yes. but this is open by default with iRedMail firewall rules.
- Not for incoming traffic.

3 Reply by swejun

  • swejun
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  • Registered: 2017-07-26
  • Posts: 84

Re: port 53 (DNS)

Can you attach /var/log/maillog when trying to send e-mail externally?

Is the mailserver configured with a valid domain, and DNS entries (MX records, A record for the Mailserver FQDN etc)?

Can You validate externally using mxtools?  https://mxtoolbox.com/

Can You use dig, nslookup or host  commands to resolve an external address, like
  host google.com
  google.com has address 172.217.20.46