Contacts name in Mail

Hi

I have some contacts whose name is incorrect. It can't be the case that the person itself has his name written wrong as in a particular case, his last name is completely not the right one.

I don't know where to look to correct this. There are no contacts in the address book or whatsoever.

Thanks

 

I looked through it, but the person that is 'wrong' is not even in the list, although he is a common person in my mail conversations.

The problem is. I've got a mail from a person which was also addressed to others. One of the other addressees as shown above the subject line has a completely wrong surname and I don't understand where it is coming from. His email address even has the correct name and surname in it.