I don't know if the webmail use POP3 orIMAP .I feel POP3

Just to clarify: the term "webmail" is typically used when mail is being accessed via the HTTP(S) protocol, in combination with some special web frontend software that "runs in the browser"...

As to the attachments: mail messages with attachments usually come in so-called "multipart MIME" format. Once you have fetched the message from the mail server (e.g. via POP3), you'll have to decompose it into its individual components. There are several CPAN modules for handling MIME stuff, for example the MIME-tools package, which also includes examples.   (but this isn't the only one...)