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I have put private server on Debian, I would like to be able to send mail but port 25 is blocked by my ISP. I checked it by opening a telnet connection to another mail server.
The good news is that I have an open port 587 on which you are connected to an external mail server.
How to set the server to send mail on port 578 instead of 25.
Please help!
Marcin Grochulski
Posted 2013-03-30T23:14:13.500
Reputation: 33
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The answer is you can't send email to the wider world (on the standard SMTP protocol) if your ISP is blocking it - you would need to either work around the block, or relay your email through your ISP.
Port 587 (Submission) is used to send emails into your mail server, ie from an MUA (like outlook, thunderbird) to an MTA (Like postfix, sendmail). MTA's speak to each other on port 25 by default.
Your ISP is probably blocking port 25 to reduce the amount of spam coming from infected customers PC's. The answer is to either get them to unblock port 25, or set up their mail server as a relay so your mail server shoves all email to them. (Or, you could get a VPN and bypass your ISP's mail block - personally I don't like ISP's which block port 25, although I do understand the business case)
davidgo
Posted 2013-03-30T23:14:13.500
Reputation: 49 152
1Which mail server software are you using? Also, are you trying to relay all mail through a single external server, or are you trying to send mail directly to recipients over port 587? – user1686 – 2013-03-30T23:35:13.837