Error sending "reset password" email

[epessina]

When resetting a user's password, the following error occurs when sending the email:

An error occurred while trying to send the email: [Errno 111] Connection refused

No further logs can be retrieved from the frontend, since the request correctly responds with a 200 status code: the error is only shown as a warning in the response HTML page (which, by the way, also displays a success message), and the mail is not sent.