SMTP email test failing even using MailTrap as recommended

Within the Newsletter plugin I've tried to test the SMTP connection by entering the credentials from MailTrap (recommended in your blog on 20 Feb 2017, https://www.thenewsletterplugin.com/test-newsletter-delivery-mailtrap) but I'm still not able to connect. What I've tried:

1. Port 25: this results in a timeout
2. Port 465: also results in timeout
3. Port 2525: "unable to connect to smtp.mailtrap.io:2525 (Connection refused)". Full display below`
   2019-05-21 00:25:24 Connection: opening to smtp.mailtrap.io:2525, timeout=300, options=array ()
   2019-05-21 00:25:25 Connection: Failed to connect to server. Error number 2. "Error notice: stream_socket_client(): unable to connect to smtp.mailtrap.io:2525 (Connection refused)
   2019-05-21 00:25:25 SMTP ERROR: Failed to connect to server: Connection refused (111)
   2019-05-21 00:25:25 SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting`
4. Port 587: "Count not authenticate". Excerpt from the full display below `
   2019-05-21 00:27:13 SERVER -> CLIENT: 535 Incorrect authentication data
   2019-05-21 00:27:13 SMTP ERROR: Password command failed: 535 Incorrect authentication data
   2019-05-21 00:27:13 SMTP Error: Could not authenticate.
   2019-05-21 00:27:13 CLIENT -> SERVER: QUIT
   2019-05-21 00:27:13 SMTP -> get_lines(): $data is ""
   2019-05-21 00:27:13 SMTP -> get_lines(): $str is "221 box5181.bluehost.com closing connection
   "`

I'm at a loss - what else should I try to resolve this?