Error: A problem occurred while sending the email. Please revise your settings. (Error: Email could not be sent. Check your mail server log)

[jtr]

Please search the forum. You’ll need to do some additional data gathering:

Nextcloud 30.0.5

Please follow the troubleshooting steps in the email chapter of the Admin Manual. After doing that, if still stuck, please fill out the support template otherwise it’s nearly impossible to provide assistance.