I have four emails connected to Outlook on my computer all from webmail06.register.com All accounts were connected and working great up until about three hours ago when I begin receiving the #5.5.1 error message for any outgoing or incoming mail. I reset the main account information and it synced up with my email account ONCE, updating my email and allowing me to send one email. Within ten minutes, however, I was receiving the same #5.5.1 error. I have tried resetting each account twice with all of the same information; it seems to have stopped being able to authenticate for my computer.

I also checked my email function on the main website for each email account and the website and my email function seems to be working fine. What seems to be the connection issue? Since the website seems to work, the account information hasn't changed, there was one successful authentication and then repeated failure? 

Thank you

AmrieG