It is not possible to send email from a Plesk server on Google Cloud or a private physical server. Incoming mail is received successfully, but outgoing messages are stuck in the queue.
How to send an email from a Plesk server on Google Cloud or a private physical server?
To configure sending emails, use one of the following solutions:
- Use one of Compute Engine’s third-party partners (SendGrid, Mailgun, and Mailjet) to set up and send emails through their servers.
Note: All these services have a free tier for the Google Cloud customers - 12,000 emails/month on SendGrid, 10,000 emails/month on Mailgun, and 6,000 emails/month on Mailjet.
- Use a Google Workspace account to set up a relay service to send emails through it. Follow the instructions for SMTP relay service settings in the Google Workspace documentation.
By default, Google Compute Engine blocks 25, 465, and 587 SMTP ports and does not allow outbound connections on them. Instances still can receive emails, while sending emails from these ports is not allowed.