eMail can only be sent when connected to WiFi

Now that I am home I can explain much better. Maybe it will help others. I activated iCloud on my iPhone to access keychain last week. Without thinking I guess I activated or reactivated iCloud mail, which I never use. In any event, from that time forward I could not send any email unless I was connected to wifi. Cox, t-Mobile, and Apple all tried to help. Apple even was able to view my screen via wifi on 26 APR and after deleting and putting the account back in, we verified all was well. Sent some tests and I was very satisfied. On 29 APR I needed to send an email from my phone and it would not send. Called Apple again and they viewed the screen, verified that all settings were correct and test emails sent with no problem. Today, again needing to send an email, I hit send and nothing. Out of frustration, I deleted and re-entered mail data. I noticed iCloud mail was on and remembering a problem I encountered on my 2009 iMac when I first got it and set up iCloud, I turned it off. Mail sent successfully. I was told by the folks at Apple that having iCloud mail on would be no problem but for some reason, it did keep me from sending. So all is well. I need to research and find out why iCloud email would cause such a disruption but for now I am quite content. Thanks you.

I use the Apple Mail thru Cox via t-mobile. I turned off I-cloud mail. Problem appears solved. Thanks