After configuring the plugin, it seems that the username and password (or lack there of), isn't getting passed to the SMTP server.

I have a username/password credentials id configured (named `shared-email-account`). Which I'm attempting to use to authenticate to `smtp.office365.com`, but it appears that when Jenkins is trying to send the email, it's trying as a different user:

DEBUG SMTP: protocolConnect returning false, host=smtp.office365.com, user=jenkins, password=<null> 

I have attached a minimal config from JCasC and the console output.