Jorgeoa I note that the Nextcloud docs state the following:
In most cases the SMTP option is best, since you will be able to control all of your mail server options in one place, in your mail server configuration then.
Based on that, my recommendation is that you use SMTP with a dedicated mailbox and address.
If you want to use sendmail with Nextcloud anyway:
- Go to https://my.opalstack.com/apps/.
- Click the Edit icon for your Nextcloud app.
- Enable the "App Exec" option - this enables PHP functions like
exec() which are used by Nexcloud to detect sendmail.
- Click "Update Application" to save your changes.
Wait a few minutes then reload the email settings page in Nextcloud. The sendmail option should then be available in the dropdown list.
