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I have tried all the solutions on your website. I receive my Cox mail, but I cannot send an outbound message on iPhone mail, Outlook 365, or Windows 10 mail. The only way I can send is from Webmail on your site. You need to correct this as it is a constant recurring problem.
What settings have you tried for outbound? SMTP server? SSL vs TLS? Port?
In general, I suggest SMTP.cox.net with SSL on port 465. Make sure you are also using you username/password for outbound.