Unable To Send Email Sender Address Rejected By Server On iPhone

Perform the troubleshooting instructions given below to fix the iPhone device unable to send the email message to the address that is rejected by the server.

• Step 1:
  First, delete and re-add your email account to the iPhone device.
• Step 2:
  If the first method does not work, restart your iPhone.
• Step 3:
  After restarting your iPhone, try to send an email.
• Step 4:
  If the issue has not been resolved, check the SMTP settings.
• Step 5:
  Switch on your iPhone, navigate to the Accounts & Passwords section, and sign in to email account.
• Step 6:
  Check if the SMTP Server option is enabled on the Account Information screen.
• Step 7:
  If not, enable it and then try to send the email.