We’ve made the difficult decision to discontinue the Yahoo Communities effective Jan 24, 2019.
Be assured you will still be able to find answers to your Yahoo product and app questions on the Yahoo Help website (https://help.yahoo.com). In addition, you’ll be able to find the Yahoo Community moderators on Twitter, responding from our many handles including @YahooCare and @YahooFantasyCC.
If you ever need help with your Yahoo accounts, try Yahoo Account Pro for 24/7 live phone support.
Are you trying to do this from a laptop, desktop, phone, or tablet? What browser or app are you using to do this? What version of Yahoo mail are you using? Are you seeing any error messages when you try to do this?
What kind of phone are you using and what is the name of the app you are using? Can you sign into this account from a laptop or desktop and sends emails?
Have you tried sending from https://mail.yahoo.com via your personal computer/laptop to see if you encounter any issues?