This issue can occur with iPhone users. If they are unable to send their excel file, they may not have set up their email properly. We can check with users by giving them the following instructions: 

  • Go to your iPhone Settings
  • Select "Mail"
  • Select "Accounts"
  • Select the email you are using (example: Yahoo) 
  • Click on "Account" where your email address is listed 
  • Select what is under "Outgoing Mail Server" 
  • Click on the "Primary Server"
  • Re-enter your username and password 
  • Select "Done" in the top right corner - this will ensure the email is set up properly 

Here are some additional references: 

  1. (video demo)