Problem passing Special character plus (+) in QueryString in ASP.Net

i am doing user authentication from mail. so i am sending the email and encrypted pass to user. and user clicking on the link getting the value of query string

http://localhost:1033/return_mail.aspx?e=pradeephellofriend@gmail.com&l=1+E4Hccj9hE=

this l=1+E4Hccj9hE=

the value of l is "1+E4Hccj9hE="

but when i am getting the value of the query string the value of l is getting "1 E4Hccj9hE="

string password = Request.QueryString["l"].ToString();