Sending Emails in WordPress from Google Cloud Instance

Did you know that Google Compute engine does not allow outbound connections on port 25,  465 and 587?

By default design, these SMTP ports are not listening by as they are susceptible to a large amount of abuse. Even though standard email ports are blocked, you can choose a non-standard port to send email through.

While sending email from blocked ports is not allowed, your instances can still receive email but remember Port 25 is always blocked and cannot be used, even through SMTP relay using G-Suite.

Sending Emails with WordPress

Choose a third party Email Service and learn how to send emails from your WordPress Server.

Having a trusted third-party provider such as SendGrid, Mailgun, or Mailjet releases Compute Engine and you from maintaining IP reputation with your recipients. 
SendGrid, Mailgun, and Mailjet are Compute Engine’s third-party partners that offer a free tier for Compute Engine customers to set up and send email through their servers.