charter email will not send

My charter.net email does not work anymore when I send. I tried Charter/Spectrum support, then apple care, then back again, then back to apple again. Tried every setting possible. Still nothing. I finally talked to one Spectrum support rep and she basically said Spectrum doesn't want customers to use third party apps or services anymore and stopped connecting to them except for legacy users ( of which I am) so that doesn't make any sense. Anyway, she recommended Microsoft Outlook email vs Apple Mail. Any thoughts on this?