trying to retrive the email address from each persons ow in Gridview?

hi,
I have  a gridview bound to Objectdatasource which retrieves data from database called PERSONS
Each person has a PersonId of Type GUID unique Identifier
PersonId -primary key -Unique Identifier
FirstName
Email address
there is also a table called campaign
CampaignId - primary key INT
PersonId  unique identifier -foreign key

In the gridview I then return all rows from Persons table based on CampaignId
(which is a query string parameter)

So If 10 persons are grouped by same CampaignId - my gridview
will show all 10 records.
I now on button click want to send an email to each of the persons in the gridview.
So I need a method to get the email adress of each one in the gridivew and
pass this asp.net system mail.

thank you for examples