4.3.2.16. Failed login attempt to WebMail classic

The "Failed login attempt" error when logging into WebMail classic may occur in the following situations:

• The service associated with the mailbox has not been paid for. For hosting account mail, you need to pay for the hosting account or renew it on credit. For corporate mail, the service owner needs to recharge the balance and unblock it.
• The login and password entered on the WebMail classic login page are incorrect. You need to find out the correct credentials and use them.
• App passwords are enabled, but the primary password is used instead of the app password when logging in. You need to find out and use the correct app password.
• When connecting to an IMAP mailbox, more than 40 simultaneous connections are established. This may be caused by a mail client that creates too many connections (which should not happen in normal operation), or by too many users working with the mailbox from the same IP address at the same time.