The user probably has an invalid email address in the user table, double check. Delete and enter again, make sure you use alphanumeric characters only.
If you use a customized email template, make sure you don't have a line with "To:".
Thanks so its a valid email address - to check I used the email address in the Email Settings as the recipient and that worked as that email address received an email saying - This is a test email sent by Symfony Mailer)
However on Change password I still get the error - if I request a passwords reset I get no error but I never get an email
So this is the log - I have masked my email and domain name
\[2026-01-19T12:59:28.507977+00:00\] app.DEBUG: SELECT t0.user_ID AS user_ID_1, t0.Display AS Display_2, t0.Observatory_notes AS Observatory_notes_3, t0.Longitude AS Longitude_4, t0.Latitude AS Latitude_5, t0.`order` AS order_6, t0.email AS email_7, t0.password AS password_8, t0.UserLevel AS UserLevel_9 FROM contributor t0 WHERE t0.email = ? LIMIT 1 {"params":{"1":"#######@outlook.com"},"types":{"1":{"Doctrine\\DBAL\\ParameterType":0}},"executionMS":0.0002551078796386719} [ ]
\[2026-01-19T12:59:28.510032+00:00\] request.CRITICAL: Uncaught PHP Exception Symfony\\Component\\Mime\\Exception\\LogicException: "An email must have a "To", "Cc", or "Bcc" header." at Message.php line 128 {"exception":"\[object\] (Symfony\\Component\\Mime\\Exception\\LogicException(code: 0): An email must have a "To", "Cc", or "Bcc" header. at /var/www/vhosts/#####.org/#######.org/vendor/symfony/mime/Message.php:128)"} [ ]
\[2026-01-19T12:59:28.538911+00:00\] security.DEBUG: Stored the security token in the session. {"key":"\_security_main"} [ ]
\[2026-01-19T12:59:28.541410+00:00\] doctrine.INFO: Disconnecting [ ] [ ]