Why is the sender address domain@domain.com when i send mail through the webmail?

The address is This e-mail address is being protected from spambots. You need JavaScript enabled to view it This e-mail address is being protected from spambots. You need JavaScript enabled to view it if you log in with the main account, dXXXX, as the main account is not connected to a specific email address the webmail needs to use another address, and chooses domain@domain.com This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

If you want to use OTHER@domain.com This e-mail address is being protected from spambots. You need JavaScript enabled to view it you can change sender address under settings in the webmail