# Bytemark SMTP

Bytemark SMTP is a lightweight Docker image for Exim 4 that lets linked containers send outgoing email. It is open source and self-hosted, installable on Docker Hub and Unraid.

Canonical page: https://ourlocalhost.com/app/541/bytemark-smtp

## Description

Bytemark SMTP is a lightweight Docker image for Exim 4 that lets linked containers send outgoing email. It can deliver mail directly to recipients or act as a smart host that relays mail to an intermediate server such as Gmail or SendGrid. It gives homelab applications a simple outbound mail relay without running a full public mail server.

## Platform availability

Available on 1 of 9 platforms: Unraid.

## Health score

21/100 (Low), based on 3 of 4 factors.
- Maintained: 0 (last commit 3021 days ago)
- Popular: 43 (145 GitHub stars)
- Easy to install: 35 (1 install platform, install notes, Docker image)

## Links

- GitHub: https://github.com/BytemarkHosting/docker-smtp
- Docker Hub: https://hub.docker.com/r/bytemark/smtp/
- Unraid: https://ca.unraid.net/apps/bytemark-smtp-0qkpp5c1fifpv8?q=bytemark-smtp

## Common questions

### What hostname and port should linked containers use to send outgoing email?

Linked containers can connect to the SMTP container using hostname mail and port 25.

### Can bytemark/smtp relay mail to an intermediate provider?

Yes. It can act as a smart host and relay mail to an intermediate server such as GMail or SendGrid.

### Is bytemark SMTP available as an Unraid template?

An Unraid template repository support thread includes a bytemark SMTP container image.

### If host-level telnet to an outgoing SMTP server works but container mail fails, what may be causing it?

A Docker networking issue may be the cause. In one report, the same setup worked on another host without the Docker network, so inspect the Docker network configuration.

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Source: Our Local Host (https://ourlocalhost.com/app/541/bytemark-smtp), the self-hosted and open-source app directory.