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Resolved SMTP Mail Not Working

sercan

New Pleskian
Hello there,
I'm having trouble sending mail for the plesk server I've set up on Google Cloud.

I know port 25 is closed in Cloud. For this reason, I checked the "Enable SMTP service on port 587 on all IP addresses" option in the mail settings and my 587 port is open.
My hostname setting is correct. I use the default Postfix and Dovecot as the mail server. It's plesk resolving the DNS and the MX records are correct.
I can't think of anything else to check. When I try to send an e-mail to the account I opened from the Plesk panel, I get a "Connection Error (Failed to reach the server)" error.

System Info:
CentOS Linux 8.5.2111
Plesk Obsidian Version 18.0.39

By the way, although the "Enable SMTP service on port 587 on all IP addresses" option is checked, it says that I need to open port 25 in the mail settings.
Thank you for giving a time.

Screen Shot 2021-11-28 at 05.01.12.png
 
In order to send or receive mail on the Internet your server must open port 25, because all other systems on the Internet expect this as the mail transmission port. I think that through your Google console you should be able to open port 25.
Please also see Question - Need help to open port 25 Google Cloud

Hello there,
Thank you for your answer. Port 25 is already open but Google Cloud does not allow us to open port 25. I think the reason is to prevent sending spam mail.
 
I created a SendGrid API following the instructions and connected it with Postfix. When I try to send mail, I get the error "smtp; 550 Unauthenticated senders not allowed".

Screen Shot 2021-11-29 at 00.44.28.png
 

Thank you, I understood the problem and now I have a new question.
 
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