It's rarely the same thing but firewalls or AV suites are ditched then we go over the settings. Then we have to try POP3 or IMAP settings. The too often recurring issue that you just bite your tongue since you don't want to upset the client is when the web mail doesn't work either. So they have to get that working.
FINALLY we have the issue you can't send email if you are not on COX's network. Some folk didn't know that.
I've used Outlook mail client on Windows XP (Outlook 97) through Windows 10 (Outlook 2016) - POP3 protocol. About 2 weeks ago, send mail began to fail - messages stuck in Outbox. The failure is independent of version: (2010 on Intel based laptop; 2016 on my Intel based desktop). Both systems are running Windows 10 Pro 64-bit. I've read several articles on the Net but none provided success. I've also contacted my ISP, COX, who blames Microsoft. Of course, Microsoft blames my ISP. Assuming that the copy of Outlook as well as my Profile were corrupted, respectively, I re-installed Office 2016 on my desktop, tested sending mail which failed. Then I changed my Outlook profile, tested sending mail which also failed. I'm out of options to try. Have others who experienced this anomaly solved it? If yes, please share you solution. Thanks for your support

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