I'm using rails 2 for this app, with ActionMailer, but this is a general question about emails.
When we send out emails, i save a record corresponding to the email in a database table. I'd like to keep track of whether people have read the emails, and am wondering the best way to do it. On initial googling, it seems like i've stumbled into an ongoing battle between spammers and email clients!
My first thought was to use the "read receipt" header, but i know that this isn't supported by a lot of clients and is therefore unreliable. After that, i read of the tactic of including an image in the mail, and of detecting that image being loaded. I was thinking that i could put a parameter with the email record's id in the image url, so that when i get a request for that image i can see if it has a (for example) email_id param and if so, mark the corresponding email as having been read.
But, then i remembered that many clients are wise to this tactic and specifically ask the viewer of the mail if they want to display images. Obviously they might say no.
Am i right in thinking that i can't pull in other resources, such as stylesheets, in my mail? Because if i can pull them in, i could do that same trick but with the stylesheet rather than an image.
Grateful for any advice, max