A user who uses Microsoft Office Professional Plus 2010 as his email client reported that he could no longer download email. Whenever the user would check his email, a window would appear prompting him to re-enter his userid and password. Even after I reset his password on the server, the same thing kept happening. At the bottom, right-hand corner of the Outlook window, I saw a "Send/Receive error" messsage next to a yellow triangle with an exclamation mark within it.
When I clicked on that error message, I saw "reported error (0x800CCC91): 'Your e-mail server rejected your user name. Verify your user name for this account in Account Settings. The server responded -ERR [AUTH] Plaintext authentication disallowed on non-secure (SSL/TLS) connections.'"
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