Port 25 is being blocked

Question

Port 25 is being blocked

Eric 1

In the Azure Portal I test the connection to an IP address on Port 25 and it says it is allowed. But when using telnet on the VM in Azure it does not work and is being blocked. There seems to be too many issues with Azure, maybe it is time to move back to our office.

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Answer 1

Alan Kinane 16,951 MVP Volunteer Moderator

Depending on your Azure subscription type you may find that port 25 is intentionally blocked by default. This is in place to prevent abuse of the service and stop spammers etc.

Depending on your subscription type it may be possible to have this block removed by logging a support ticket with Microsoft and requesting the block to be removed for your subscription.

Please review the details in this link:

https://learn.microsoft.com/en-us/azure/virtual-network/troubleshoot-outbound-smtp-connectivity

Answer 2

Eric 1

After posting issues with Azure my Microsoft account got hacked and spam emails were sent out to our clients. I think it was Microsoft that hacked my account since my password was long and difficult.

Sudeep Sharma 1 Reputation point

2022-03-02T18:10:46.527+00:00

If your SMTP is not configured properly, then you need to hack to your account to send the spam emails. It could be done by abusing the SMTP protocol itself. For example, an email with a valid reply addresses, sent to your SMTP address, the recipient address would be incorrect, so in this case your SMTP server would reject the email since the recipient is not a valid, but it would send the email to the reply-to address which would be the intended end user receiving the spam email.

There are lot of similar techniques spammer used and above is just an example.

Thanks,
Sudeep

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Port 25 is being blocked

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