Unable to send email messages from Mail on iPhone through Charter/Spectrum email account.

I have a charter.net email address. I have the address setup in Mail with the Charter / Spectrum Email settings document. I can receive email just fine anywhere however I cannot send mail anywhere, it is always stuck in the Outbox. Charter says everything is good on their end, and I know the setting are correct. I have deleted and re-added my account several times but get the same result.

Anyone have this issue that can help?

Thank you!