I read that some webmail services prefetch url links in emails. The GET request would then trigger my server to verify the account, regardless of whether the user did anything.
Is this true and if so, how can I work around this? I have seen a lot of websites with one-click solutions for confirming user accounts.
Never heard of a webmail service who'd pre-fetch GET links with query parameters -- that could turn out to be costly in many ways, after all. I think you'll be fine with the one-click solution you're thinking of!
Same as Alex, never heard of the pre-fetching you're talking about. I don't know if this is what you're looking for but if you're using an MVC framework, you can put in your specially crafted URL and have a large button that the user clicks to actually confirm. Using that submission (the click) from that page as the referrer and stripping out the portion of the URL, you then set your confirmed or similar column in your database.