SMTP Relay service
It’s not critical to your Matrix server’s functionality to send outgoing emails. Still, a Matrix homeserver may send out emails for the following reasons:
- when users add email addresses to their profiles - an email confirmation link is sent out to confirm mailbox ownership
- when users enable email notifications for unread rooms - after a period of inactivity, the homeserver may send a “Here’s what you’ve missed” emails
- when users use the Postmoogle email bridge and send outgoing emails through it
When do I need an SMTP relay?
By default, your Matrix server tries to send outgoing emails directly. On some networks and VPS providers this works well enough.
On other networks and VPS providers, sending outgoing email is problematic because:
- either outgoing port
- or the IP address reputation of the server is bad and email deliverability is low
In such cases, you may wish to send email through another SMTP server.
What do I do if I need an SMTP relay?
If you need your Matrix server to send outgoing emails via an SMTP relay server, you have 2 ways to go about it: