Changing look how Wordpress is sending mail

I want to make Wordpress as email sender and here is a problem i'm facing:

I'm using XYZ Newsletter plugin for sending emails. But when the person gets the email, in the persons email check program in the email field i get a whole server name instead of address.

For ex. jkdo@arboga.hostingas.in; on behalf of; Admin infoatmydomaindotcom

i need to be only the email address

And this is the same when Wordpress itself is sending a letter. May be you know where to change it ?

Have a very good day, Thank you, Justin

via Chebli Mohamed