As per http://www.php.net/manual/en/function.curl-setopt.php:
CURLOPT_SSLVERSION: The SSL version (2 or 3) to use. By default PHP 
will try to determine this itself, although in some cases this must be 
set manually.

I'd rather leave it like this, as it seems that any attempt to detect 
this on the client level would be inferior to solve it on the protocol 
or library level. I'd rather work with the PHP and/or Curl developers 
to determine what exactly "some cases" mean, and how to improve this.

Hello,

I recently shored up our SSL implementation on apache with the 
following options:

     SSLProtocol -ALL +SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2

Then I began noticing that Kronolith requests for free/busy URL 
information began to fail.  I think I've managed to trace the 
accessibility error back to the following class 
./pear/php/Horde/Http/Request/Curl.php.  Adding the following option 
seems to rectify the accessibility issue and Free/Busy URL requests 
are now succeeding:

curl_setopt($curl, CURLOPT_SSLVERSION, 3);

I know my workaround is not a good solution and was wondering if 
adding support for a fall-through like solution would be desirable?   
Perhaps higher SSL versions are tried first within the CURL class, and 
if they fail the class could then fall back to older implementations.

I appreciation your feedback.