I can’t send email using WLM following change to Charter internet provider

I cannot send email. I have tried fixes suggested by Microsoft telephone support including change to port 587 from 25, and change to 'charterinternet' for outgoing server. error message is 0x800CCCoE. I see that another person with same error code changed to 587 and that worked for him, but it doesn't work for me. I have been at this for 3 hours on line and on the phone.