I have had nothing but problems with email since Cox began "upgrading" their email service. Calls to tech support end up with no solution since Cox simply blames Microsoft Outlook for all their problems. I try Thunderbird and Windows Mail have the same problems: IMAP or POP3 and SMTP errors with both incoming and outgoing mail: Cox incoming & ougoing servers will not respond to any mail client other that Cox Webmail. I have tried and re-tried the settings on my PC and my wife's PC an untold number of times, both with and without Cox tech assistance up to Tier 2.Nothing works and they just tell me to use Webmail.
I pay $250 a month for Cox Ultimate plus phone & TV and have been a customer for 22 years and I am not happy being told what email client I must settle for, since I've ued Outlook for over 20 years on Cox with no problems until this year. Since Cox has a monopoly on high speed service in my area, I'm stuck but once I leave this area, I will leave Cox and never look back again, nor will I recommend it to anyone who has alternatives.