Recipient sees email text repeated on emails sent from Samsung Galaxy Tab 3

[AC Question]

I bought a Samsung Galaxy Tab 3 and followed the instructions for adding some email accounts to the standard email app.

However, when I send an email from the Tab, the recipient gets the email text repeated. For example if I send "Hi there!", the recipient gets:
"Hi there!

Hi there!"

Why does it do this, and how can I fix it?

 

[Seahorizons]

Hi

I get the same problem with my S6 Edge+. Did you find a solution? Many thanks.