@eLIANT Please show the debug output when trying to send a test email.
Use the code toolbar button < /> so that it is formatted as fixed width.
This is the debug output when I try to connect to your mail server using the same FROM address but made-up user and password
2021-09-26 09:14:57 Connection: opening to mail.privateemail.com:587, timeout=5, options=array()
2021-09-26 09:14:57 Connection: opened
2021-09-26 09:14:57 SERVER -> CLIENT: 220 PrivateEmail.com prod Mail Node
2021-09-26 09:14:57 CLIENT -> SERVER: EHLO strontian
2021-09-26 09:14:57 SERVER -> CLIENT: 250-mta-06.privateemail.com250-PIPELINING250-SIZE 81788928250-ETRN250-AUTH PLAIN LOGIN250-ENHANCEDSTATUSCODES250-8BITMIME250-CHUNKING250 STARTTLS
2021-09-26 09:14:57 CLIENT -> SERVER: STARTTLS
2021-09-26 09:14:57 SERVER -> CLIENT: 220 Ready to start TLS
2021-09-26 09:14:57 CLIENT -> SERVER: EHLO strontian
2021-09-26 09:14:58 SERVER -> CLIENT: 250-mta-06.privateemail.com250-PIPELINING250-SIZE 81788928250-ETRN250-AUTH PLAIN LOGIN250-ENHANCEDSTATUSCODES250-8BITMIME250 CHUNKING
2021-09-26 09:14:58 CLIENT -> SERVER: AUTH LOGIN
2021-09-26 09:14:58 SERVER -> CLIENT: 334 VXNlcm5hbWU6
2021-09-26 09:14:58 CLIENT -> SERVER: [credentials hidden]
2021-09-26 09:14:58 SERVER -> CLIENT: 334 UGFzc3dvcmQ6
2021-09-26 09:14:58 CLIENT -> SERVER: [credentials hidden]
2021-09-26 09:15:00 SERVER -> CLIENT: 535 5.7.8 Error: authentication failed: UGFzc3dvcmQ6
2021-09-26 09:15:00 SMTP ERROR: Password command failed: 535 5.7.8 Error: authentication failed: UGFzc3dvcmQ6
SMTP Error: Could not authenticate.
2021-09-26 09:15:00 CLIENT -> SERVER: QUIT
2021-09-26 09:15:00 SERVER -> CLIENT: 221 2.0.0 Bye
2021-09-26 09:15:00 Connection: closed
If you are not getting even that far, then there might be a problem with the outgoing connection being blocked on the web server.