Hi there! I'd like to try to help you with this. Are you using the Apple Mail app on your iPhone? If not, what mail app are you using? Is it freezing on *all* links you find in different emails, or just on a specific link in a specific email or from a specific sender?
Do you have any non-AOL mail accounts setup on your phone that you could test to see if those links are hanging up too? (To help identify if it's a problem specific to AOL's email.)
Also, what version of IOS do you have on your iPhone? Did you just upgrade to IOS 9 by chance?
I meant to ask, did you just upgrade to IOS 9.3?
Well, I wish I had better news for you, but: http://techcrunch.com/2016/03/28/its-not-just-you-clicking-on-links-in-ios-9-3-can-crash-your-iphone/
One article suggests that if the links you're clicking on are related to a specific app that's installed on your phone, that deleting the app and allowing the link to take you to the web page, instead of opening the app, might help until Apple can publish a fix.
Apparently Apple's support forums now have multiple threads on the matter, some of which contain 1000's of views.
I'm not sure I provided much value to your request, but did it help you understand the problem?
I'm afraid that's entirely up to Apple however, the inconvenience factor on this problem is high and since it's related to a signature feature of IOS 9 (Universal Links) so I'd say they'll have a new update for you pretty quick. Below is a quote I found on the web. I can't attest to it's accuracy, but I've seen several similar comments on different blogs and forums.
"It’s not known when a fix will come, either. One user in the forums claims Apple Support was Direct Messaging them on Twitter and says there is no known fix yet, while another commenter claims Apple Support tells them a fix is coming Monday or Tuesday."