I had this same problem just the other day, but in reverse: I was able to register for the game itself, but the system refused to send me a verification email for the forums, no matter how many times I would try. This was a huge problem for me, because for me the game wouldn't even install, and I had no way to even get help because I couldn't register for the forums. I almost gave up. How many new users could be lost to this problem?
In my case I went the extra mile and installed mirc, and went to channel #planeshift for help. Someone there was kind of enough to register an account for me using THEIR email, then they did the verification, and after that changed the email to my real address. That's the only reason I'm here and was able to get help. However, I bet a lot of new users don't have the know-how to connect to IRC and thus would be out of luck totally.
Anyway, I have something to add about this verification email problem. There is another reason why the verification fails other than the ones given in the sticky. I'm not completely sure what that reason is, but I can make a pretty good guess (which I'll get to in a minute). In any case I can prove it wasn't my ISP blocking the email, but rather that the system is incapable of sending the verification email to me -- I can prove that the problem in my case is on the planeshift side. How can I prove this? Well, I did a screen capture of the message I received every time I tried to have account verification resent. I received an error every time. I saved this screen capture as a PNG file, and would upload here to this post but I don't see the option to do that -- maybe that's not allowed. Anyway, if anybody working on this problem would like me to send them this screen capture, just msg me with an email address I can send it to. It's not an informative error message though...it just says "An Error Has Occurred".
So what exactly is the cause of this error? As I said above, I have a guess. Remember that I said someone registered for me, and then changed the email address to mine? Well, when I go to my profile page to see the official email address associated with my account, my address is there...but with the last character cut off. So instead of ending with ".com" it ends with ".co". Of course, any attempt to send an email to an address ending with ".co" would result in an error. So, why is it cutting off the last character? Well, my email address is 21 characters long. I believe that the forum system is limiting email addresses to only 20 characters. That's my guess. If this is the case, can the number of allowable characters be increased?
By the way, this isn't just "water under the bridge" with my account. Presently, my account is sort of crippled. When I go to the profile page and make changes, they just don't take. So I can't correct my email, and I can't change my password (right now it's set to what my #planeshift helper set it to). Maybe profile changes have to be OK'd by the email address of record? Since my email address is longer than 20 characters, this is impossible. So currently I can't change my profile, and I can't receive email notifications of new posts.