Account name changed while sending email

My email is set on my name, My account name is perfectly fine with my Name as Muhammad Uns but whenever I send an email it goes with another name i.e my Girlfriend's name and this is so Embarrassing for me. Every time I send an email or somebody else is sending me an email my Name on the thread is automatically changed.

I have tried everything have corrected almost every name attached to my account but still the problem persist!!!