Yes — on rooted or unlocked Android (using Termux), you can run certain lightweight email servers. Full mail stacks (like Mailcow or Mail-in-a-Box) are not compatible.
| Maddy |  Yes |
|---|---|
| Haraka | Yes |
| Postfix + Dovecot |  Possible |
| Mox | Maybe |
| Exim | Possible |
| Mail-in-a-Box |  No |
| Mailcow | No |
| Docker Mailserver | No |
| Modoboa | No |
| WildDuck | Partial |
| Listmonk | Possible |
| Keila | Possible |
| ZoneMTA | Yes |
| Forward Email | No |