Hi

I suppose it depends on how you're tracking your emails as there are a
few different ways of (trying) establishing whether your sent emails
are read (i.e. by using the read notification properties, attaching an
image (visible or not) that identifies the email etc). A lot of these
methods don't work as well as they used to due to the clamp down on
spam (a lot of spammers used to use these techniques to identify that
the email address they sent to is actually valid and active so they
could resell the email address to other spammers etc).

If you're relying on a read-receipt then, as already mentioned, you'll
need to have some control over your end-users email app so that you can
intercept these read-receipts and deal accordingly (either that or
you'll have to get your app to talk to their main email server via pop3
or whatever, scan for any 'read-receipts' and deal appropriately before
it hits the end users app - I'd imagine this as being more problematic
to implement though to be honest).

If you go for the second approach (i.e. attaching a uniquely
identifyable image to the email that's located on a web-server under
your control) then you can monitor for access to this image and post
notification to your db as necessary.

All in all though, I would speak to your customer/end-user and let them
know that confirming an email has been read is a) no longer as 'easy'
as it used to be, and b) no where near as accurate so it really depends
on what value they'll actually gain from this.

Hope that helps
Martin