Outbound SMTP port

Question

I want to send SMTP email from a VM/Postfix . Is it possible or do I need a special permit to allow SMTP outbound port?

Answer 1

Hi ,

When an email client or outgoing server is submitting an email to mail server, it should always use SMTP port 587 as the default port.

Port 25 is the recommended port number for SMTP communications between mail servers (i.e., for relaying messages), port 587 is the one recommended for message submissions by mail clients to mail servers.

So you need to allow inbound traffic on port 587, port 25 and outbound traffic on port 25.

By the way, for SMTP related question is beyond our windows-network-access-protection support, it depends on which mail server you are using. If you are using exchange mail server, then you could ask the related question in our exchange forum. Since you are using third-party mail server (Postfix), you would better contact the vendor of Postfix for better answers.

Best Regards,
Candy

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