I have had an outlook.com and Hotmail.com account set up on my ipad and iphone for years. Now I am getting an error message when sending an email through either the iphone or ipad using either the hotmail or outlook account.  The error states "Cannot Send Mail - An error occurred while delivering this message"

I am able to receive mail to these devices furthermore if I actually go online and sign into my account I am able to send an email no problem

I have not made any changes, it just stopped working.

I dont know what it is, however I never have any issues with gmail or yahoo, I have been regrettting sticking with microsoft , too many issues

Please advise and help me to get it working

Thanks