Mail Stuck in Outbox - Tried to Delete and Add Back Email Accounts and Now Cannot Even Set Them Up

Hi, Becky - 

I am receiving the following error messages when trying to re-set up my email accounts in Outlook.  I deleted them because they were not sending email (receiving works fine) and one of the support people I spoke with at Cox told me to do so.  Please help me unravel what the following error codes mean and what I need to do to get my cox.net email accounts set up and functioning.  They were working just fine until about a month ago.  Three live chats, two phone calls, upgrading to Cox support at the cost of $10/month - all were unable to resolve.  My personal opinion is that my IP address is being blocked by Cox or one of its third party security providers, but again, everything was working fine until about a month ago.  I have a static IP address provided by air-pipe.com.  Please help.

See below for the various combinations of outgoing smtp.cox.net server port numbers and encryption selections in Outlook email set-up that I tried configuring along with the corresponding error messages I received back. 

SMTP Server Port 587 and STARTTLS encryption selection

Send test email message: Your outgoing (SMTP) email server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: 554 cxr-obgw-6002a.stratus.cloudmark.com cmsmtp 208.81.

 SMTP Server Port 587 and Auto encryption selection

Send test email message: Your outgoing (SMTP) email server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: 554 cxr-obgw-6003a.stratus.cloudmark.com cmsmtp 208.81.

SMTP Server Port 25 and SSL/TLS encryption selection

Send test email message: Outlook cannot connect to your outgoing (SMTP) email server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).

SMTP Server Port 465 and SSL/TLS encryption selection

Send test email message: Your outgoing (SMTP) email server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: 554 cxr-obgw-6002a.stratus.cloudmark.com cmsmtp 208.81.

SMTP Server Port 587 and SSL/TLS encryption selection (this should actually be the functioning combination according to your web site email settings)

Send test email message: Your server does not support the connection encryption type you have specified. Try changing the encryption method. Contact your mail server administrator or Internet service provider (ISP) for additional assistance.

SMTP Server Port 587 and None encryption selection

Send test email message: Outlook cannot connect to your outgoing (SMTP) email server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).

SMTP Server Port 465 and STARTTLS encryption selection

Send test email message: The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).

SMTP Server Port 587 and STARTTLS encryption selection (second attempt with this combination yielded slightly different error message)

Send test email message: Your outgoing (SMTP) email server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: 554 cxr-obgw-5002a.stratus.cloudmark.com cmsmtp 208.81.