complete URL in the email body

Hi

First of all, I am very very new with Ruby/Rails...I am working on
maintenance of a project with a team.

I created some tracking code for an email....created a new tracking
controller with script/generate...now all is fine...but the problem is
that I am displaying an image in the email and for that I need to
embed the complete HTTP URL with the image so the image can be
displayed in the email.

so right now the source of my image in the email is /tracking/pixel/?
sub=abc but it suppose to be http://mysite.com/tracking/pixel/?sub=abc

I am experience with PHP and know all how to do that in LAMP but total
new with Ruby/Rails so if someone can explain a little...I did hear
that it has something to do with the helper and routes but I cant find
out anything on these helpers and routes either.

Looking forward to your quick reply.

Just put the full URL string as you have shown it above in the image_tag.

Colin