Activating a link from a message

Hi.

I solved all my past problems! Now a new one has appeared … I bought and installed two add-ons, one of them was notification by mail. After registering the user on the site comes the appropriate letter to confirm the mail, but after going through the link from the letter, gives an error: Invalid activation key. Click here to get a new one! When you request a new key, a new message comes in, but the link in it is also not working … Yes, and it should be still from the first working letter, what could be the problem? Maybe there is a problem with the caching plugin, if so how do I fix it?

Thanks for the help!

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