Thanks Pari for your response,
I don't think this is the header, this is just the subject of the message.
The structure is the following :
<header> <hour the email was sent>
Where the header is usually the name of the account which sends the message.
This is an example :
If you know the answer, I'll apreciate your help.
I found the solution for your Query,
I tried it and its working fine for me
just use the below line and it will change header for you,
objEmail.From = """Hi How are you"" <firstname.lastname@example.org>"
Hope this will help for you,