Question: having some issues upgrading my Sitefinity 4.1.1339.0 installation to 4.3 (and ultimately to Sitefinity 5). It is giving me the following error: 

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> > Could not load file or assembly 'Telerik.Sitefinity, Version=4.1.1339.0, Culture=neutral, PublicKeyToken=b28c218413bdf563' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
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I was thinking it was the /bin/Telerik.Sitefinity.dll file but everything seems to be updated in there.

Any ideas?
Thanks!

Answer: 
I'm not sure I understand what's going on here, but are they complaining about the data going from the form to the "http://website/script.asp" without being checked?

Because, if so, then that's just ridiculous because even if you *chose* to do some JavaScript / other client-side checking, one should never rely on it. All the sanitisation should be done server side, which I presume it is?

Could you post the original script for clarity?
Your script is immediately at risk because you're blindly using $\_POST for your email headers. This could allow a person to manipulate the header of the email to send to a wildcard email address, or simply use your form on your server to send spam to others. 

With a content type of HTML, you should run `htmlentities()` on the user input ( Assuming you don't really want them to have HTML fire off in an email viewer as mentioned).

Additionally, look into `filter_input()` to ensure the email address they're entering is valid and not header injection.

<http://us2.php.net/manual/en/function.filter-input.php>