SMTP-Mailer is configured automatically and working for me when I send the test email. However, a number of Contact Form plugins that were advertised as working with SMTP-Mailer weren't actually sending an email. Some failed silently, and some helpfully showed an error to the user.
I did finally find one. Completely free. I'm not connected to them in any way. Just leaving this here in case anyone else runs into the same problem.
Success! Thank you!
It won't let me change it.
root@sftp:/etc/ssh# chmod 600 ssh_host_rsa_key
chmod: changing permissions of 'ssh_host_rsa_key': Read-only file system
root@sftp:/etc/ssh# sudo chmod 600 ssh_host_rsa_key
chmod: changing permissions of 'ssh_host_rsa_key': Read-only file system
SFTP service is flashing orange in Services panel.
Upgraded to Ubuntu 22 followed by Ubuntu 24 following the guides on the site.
sftp service log after a service restart
Dec 03 19:34:27 [GET] /healthcheck
Dec 03 19:34:27 2025-12-04 01:34:27,895 sftp proftpd[42]: LDAPServer: parsed URL 'ldap://172.18.0.1:3002/??sub' as 'ldap://172.18.0.1:3002/??sub'
Dec 03 19:34:27 2025-12-04 01:34:27,899 sftp proftpd[42]: fatal: SFTPHostKey: unable to use '/etc/ssh/ssh_host_rsa_key' as host key, as it is group- or world-accessible on line 76 of '/etc/proftpd/proftpd.conf'
Dec 03 19:34:27 2025-12-04 01:34:27,904 WARN exited: proftpd (exit status 1; not expected)
Dec 03 19:34:31 2025-12-04 01:34:31,258 INFO spawned: 'proftpd' with pid 46
Dec 03 19:34:31 2025-12-04 01:34:31,301 sftp proftpd[46]: LDAPServer: parsed URL 'ldap://172.18.0.1:3002/??sub' as 'ldap://172.18.0.1:3002/??sub'
Dec 03 19:34:31 2025-12-04 01:34:31,303 sftp proftpd[46]: fatal: SFTPHostKey: unable to use '/etc/ssh/ssh_host_rsa_key' as host key, as it is group- or world-accessible on line 76 of '/etc/proftpd/proftpd.conf'
Dec 03 19:34:31 2025-12-04 01:34:31,308 WARN exited: proftpd (exit status 1; not expected)
Dec 03 19:34:32 [GET] /healthcheck
Dec 03 19:34:32 2025-12-04 01:34:32,020 INFO gave up: proftpd entered FATAL state, too many start retries too quickly
Have restarted host (Digital Ocean droplet).
Have rebooted Cloudron.
Have confirmed /etc/ssh/ssh_host_rsa_key permissions are 600 and owned by root
Have discovered that /etc/proftpd directory does not exist at all (making the error message mentioning line 76 particularly strange).
https://paste.cloudron.io/iyasudamap
9.0.13
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 24.04.3 LTS
Release: 24.04
Codename: noble
Manual with ./cloudron-setup
(I think. It was a very long time ago).
cloudron-support --troubleshootVendor: DigitalOcean Product: Droplet
Linux: 6.8.0-88-generic
Ubuntu: noble 24.04
Processor: DO-Regular
BIOS pc-i440fx-6.1 CPU @ 2.0GHz x 2
RAM: 4009880KB
Disk: /dev/vda1 14G
[OK] node version is correct
[OK] IPv6 is enabled in kernel. No public IPv6 address
[OK] docker is running
[OK] docker version is correct
[OK] MySQL is running
[OK] nginx is running
[OK] dashboard cert is valid
[OK] dashboard is reachable via loopback
[OK] No pending database migrations
[OK] Service 'mysql' is running and healthy
[OK] Service 'postgresql' is running and healthy
[OK] Service 'mongodb' is running and healthy
[OK] Service 'mail' is running and healthy
[OK] Service 'graphite' is running and healthy
[OK] box v9.0.13 is running
[OK] netplan is good
[OK] DNS is resolving via systemd-resolved
[OK] Dashboard is reachable via domain name
[OK] Domain sethfeldkamp.com is valid and has not expired
[OK] unbound is running```