The server refused your credentials.
CHECK IN THIS ORDER
- The username is the FULL email address, not the part before the @.
- The password is current. Reset it in cPanel > Email Accounts and type it in manually rather than relying on autofill.
- The password was not truncated by the client. Some clients silently cut very long passwords; if yours is unusually long, try a shorter strong one.
- Caps lock, and characters that look alike: capital I, lowercase l, and the digit 1.
IF THE PASSWORD IS DEFINITELY CORRECT
Repeated failed attempts trigger a firewall block on your IP address. Once blocked, even the correct password fails because the connection never reaches the server.
Test from mobile data with wifi off. If it works there, you are blocked. Open a ticket with your address from whatismyip.com.
THE MOST COMMON UNDERLYING CAUSE
A phone or second computer still holding the old password after you changed it, retrying every few minutes until the firewall blocks the whole connection. Update every device, including ones you rarely use.
