Sending mail¶
Outgoing mail leaves one of two ways:
- Directly. The server looks up each recipient's mail servers and delivers to them itself. No third party and nothing to pay, but it needs port 25 open to the internet, an IP address with a clean reputation, and reverse DNS that names this server.
- Through a relay. A service such as Amazon SES or Mailgun takes the mail and delivers it for you, and looks after reputation. This suits a home connection, or a cloud host that blocks port 25. It costs a little, and the service sees your outgoing mail.
The sending guide¶
How this server sends mail is on Settings › Overview and at the top of Settings › Mail flow › Routes and relays. It starts by saying which way the server sends now.
- How mail leaves. Check tries port 25: it connects from this server to a big mail provider's servers and waits for their greeting. Nothing is sent. It says whether port 25 is open, looks blocked (usually by your host), or couldn't tell. Then pick Deliver directly or Through a relay service.
- Relay service. Amazon SES, Mailgun, SendGrid, Postmark, Brevo, SMTP2GO, or another relay such as your ISP's. Each fills in its server, port and encryption, with a region where the service has more than one.
- Sign-in. The user name and password the relay gave you. The password is kept in the server's settings like other secrets, and never shown again.
- Review. What will change, and what is left as it is. Routing rules you made yourself still apply first, before the guide's fallback.
- Test it. Send a message from the webmail to an address outside your domains, then watch it under Management › Emails › History › Outbound delivery, where each attempt shows the answer from the other side. If it waits in Management › Emails › Queued, its last error says why: for a relay, usually the sign-in, or a sender domain the relay hasn't verified yet; directly, often port 25 being blocked or the other side refusing this server's IP.
The changes are written one at a time. If one is refused, the ones before it are put back, so a failed attempt leaves things as they were.
To change your mind, run the guide again and pick the other way. A relay you set up stays saved, unused, so switching back is quick. The delivery strategy and routes it writes are under Settings › Mail flow › Sending, for anything it doesn't cover.
Limits¶
A new server has no rate limits at all, so one stolen password can send as much as it likes. Sending and receiving limits, on Settings › Overview, sets sensible ones for who uses the server:
| Me and my family | A company or school | Open to the public | |
|---|---|---|---|
| Connections a minute from each outside server, on port 25 | 20 | 60 | 300 |
| Messages an hour each signed-in person may send | 100 | 500 | 100 |
| Recipients an hour each signed-in person may address, across all their messages | 500 | 2000 | 500 |
| Deliveries a minute to any one receiving server | 30 | 60 | 120 |
| Messages each sender may have waiting to be delivered | 500 | 2000 | 500 |
Each number can be changed before it's saved. Going over a limit loses nothing: an incoming connection is told to try again later, and an outgoing delivery waits in the queue until the rate allows.
The guide's rules start with "Preset:", and it only ever changes its own. Rules you add by hand are left exactly as they are. To undo, run it again, or switch any rule off in its list.
The rules are under Settings › Mail flow › Limits: Incoming rate limits, Outgoing rate limits and Queue quotas. Each list opens with its rules as sentences ("Each signed-in person may send 100 messages an hour.").