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Aside from the intermittent "can't sign in to email server" error popups that have been happening for more than SIX MONTHS, now both my wife and I can't send emails on her iPhone 8 and my Galaxy S8. The server settings are correct.
I need this fixed NOW!
Probably not since there are plenty of people reporting this problem and have been for a long time. JUST FIX IT!
You are right, there has been TONS of problems with email, but honestly, most of them latly has been with Cox's new webmail website and Cox's website in general. I have been telling people to use email clients instead, so I hope that isn't broken too. I really think your issue could be your using port 587 instead of port 465. Your settings are correct for the old system, just not the new one that changed about 6 months ago. However it's possible the email username didn't migrate over until more recently.
What I think is happening is your newer phones are trying to use TLS 1.1 but Cox's SMTP servers are only compatible with TLS 1.2. The servers should negotiate that fact correctly and fail safe to SSL, but some clients error out instead. The solution is to use port 465, which attempts SSL first, instead of TLS. See this thread here for more info, but it is very technical. What further complicates the issue is the OSX Mac Mail app support TLS 1.2 for SMTP but NOT IMAP. Last, if you sync the Cox email account with Icloud, then Icloud demands TLS 1.3, which Cox isn't compatible with at all. Keep in mind this is all based on my testing, so if Cox can confirm/deny anything, that would be helpful.
Did a phone reset on my android phone and for the life of me I could not connect to the outgoing mail server any longer. Tried all of the ports and security settings I could find and it simply would not connect. It turned out that while attempting to connect I was always connected to the Wifi at work and I believe that is why it wouldn't connect to the server (not sure why). When the wifi disconnected and I tried again it worked (Wow! Alot of wasted time)