services.nextcloud.settings.mail_smtpmode

Which mode to use for sending mail. If you are using local or remote SMTP, set this to smtp. For the sendmail option, you need an installed and working email system on the server, with your local sendmail installation. For qmail, the binary is /var/qmail/bin/sendmail, and it must be installed on your Unix system. Use the string null to send no mails (disable mail delivery). This can be useful if mails should be sent via APIs and rendering messages is not necessary.