It's probably not illegal, for that you'd have to get the advice of a lawyer, but I am certain that it is against their Terms of Service. For example:

Yahoo! grants you a personal, non-transferable and non-exclusive right and license to use the object code of its Software on a single computer; provided that you do not (and do not allow any third party to) copy, modify, create a derivative work of, reverse engineer, reverse assemble or otherwise attempt to discover any source code, sell, assign, sublicense, grant a security interest in or otherwise transfer any right in the Software. You agree not to modify the Software in any manner or form, or to use modified versions of the Software, including (without limitation) for the purpose of obtaining unauthorized access to the Service. You agree not to access the Service by any means other than through the interface that is provided by Yahoo! for use in accessing the Service.

Despite this, the German computer magazine c't just published a howto on retrieving your e-mail from webmail services using Perl and LWP. You might be able to glean some useful information from it (even if you don't speak German).

--
Allolex

In reply to Re: legality of extracting content from websites by allolex
in thread legality of extracting content from websites by jasonbasic

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