DigitalOcean使用587端口通过gmail发邮件

Stopping spam is a constant fight and due to this, your account has restrictions specifically on ports 25 and 465. However, you are be able to send out mail using port 587. You will need to open the port in your firewall.

We realize this is inconvenient, but many customers in your position move their mailing activities to a third party service such as SendGrid or similar which processes such mail separately from their droplet. I'm sorry for the frustration but we're not able to lift these port restrictions at this time.

In terms of a workaround, here are a few alternatives:

1. Utilize port 587 for SMTP relay via another mail provider, for example G Suite/Gmail, Mailgun, etc. We have a guide on doing so using Postfix here:

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-mail-relay-with-postfix-and-mailgun-on-ubuntu-16-04

1. Configure your app or service to send mail directly using either a SMTP client connection (typically using port 587), or API call via another mail provider such as Sendgrid, Mailgun, Mandrill, etc.

Please note that with this restriction in place on port 25, mail servers hosted here will be unable to directly relay email to other mail servers, as communication between mail servers typically takes place on port 25.

We think the API is the best solution, as it is honestly more scalable and what we would use if we wanted to "future proof" the project.

Please feel free to reach out to us via this ticket if you have further queries or concerns, we will be around to help you out!

Regards,

Saurabh
Developer Support Specialist - DigitalOcean

(Check out our fantastic community articles: https://www.digitalocean.com/community)