Your password may be fine. Work through these in order.
Setting this account up for the first time?
Mail can show this message at the Sign In step on a new account. That is expected. Continue, then enter the server details from Email settings.
It was working and then stopped
1. Test your password in webmail. Go to yourdomain.com/webmail, using your own domain, and sign in with your full email address and email password. Type the password by hand, because a saved one may be out of date. If that fails, the password is wrong: change it. Your email password is separate from your EverWeb account password.
2. Unblock your connection. Too many wrong password attempts can block your IP address. On the Mac that shows the error, sign in to your client area. That clears the block. If iCloud Private Relay or a VPN is on, turn it off first, then sign in again.
3. Check Mail's settings. Go to Mail > Settings > Accounts, select the account, then open Server Settings.
- Uncheck Automatically manage connection settings for incoming and outgoing.
- User name: your full email address
- Password: your email password, in both the incoming and outgoing sections
- Host name: your server name (where to find it)
- Incoming port: 993, SSL/TLS on, Authentication: Password
- Outgoing port: 465, SSL/TLS on, Authentication: Password
4. Remove the account and add it again. With an IMAP account, your mail stays on our server. If your account is POP, check first: mail may exist only on this Mac. See Cannot verify identity of server for how to check.
Still stuck?
In Mail, choose Window > Connection Doctor, wait for it to finish, take a screenshot of the full message, and send it to support with a screenshot of your Server Settings. Leave your password out of the screenshot.