SMTP Mail Sending Failure port 465

Question

Good day.

I am currently trying to send an email using Aveva Edge 2023 software on port 465 through the smtp.gmail.com server but it cannot send.

I am using the trial version for 1 month and I understand that for these versions the email output through port 25 is blocked.

I would like to know if there is a block by Azure for my test of sending mail through port 465.

I am attaching the logs with the wireshark software to see if it is of any help.
https://drive.google.com/drive/folders/1R6wyzqOkeHtv7foWat1JyfTsUdr7A4_I?usp=sharing

In advance thank you very much for the help.

Answer 1

Hello @Luis Alfredo,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

Azure only blocks outbound SMTP connections on TCP port 25 for few subscription types.

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

Azure recommends using authenticated SMTP relay services to send email from Azure VMs or from Azure App Service. (These relay services typically connect through TCP port 587, but they support other ports.) Using these email delivery services isn't restricted in Azure, regardless of the subscription type.

I checked the logs and can see that port 456 is open. The TLS handshake is happening just fine, and I can also see some encrypted Application data being transferred. But then there is a TCP reset at the end (I believe sent by the application). It looks like an application issue.

I would request you to check the application for any issues and further troubleshooting.

Regards,

Gita