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[Solved] Cannot received mail if 25 port are blocked on firewall

Ilya Andriyanov
Joined: 6 months ago
Posts: 1
Topic starter  

I have blocked all ports except:
- 143, 110, 993, 995, 587

This is enough (587port) to send a message. 

But If someone send me emails, I don't receive them. At the same time, others do not receive errors that the letter has not been delivered. If I unlock\allow port 25, then the emails arrive, even those that were previously stuck.

Joined: 8 years ago
Posts: 39

Hi Ilya and welcome to zextras community!

All the comunication between servers must be over port 25 as the standard of SMTP protocol.

Ports 587 or 465 is only for clients ( send email from your client to your server ).

I suggest you to open all tcp traffic for port 25 (in/out) or you are not be able to receive or send email to an external server.