The famous libnet modules provide Perl programmers with a low level interface to POP3 and SMTP servers, among others.
This works fine in general but over the past years most mail servers stopped offering 'plain' SMTP and POP3 access, but use either SSL or TLS encryption. This has lead to a plethora of modules on CPAN to support SMTP via SSL or TLS and also for POP3 via SSL. Until recently this was not the case for POP3 using TLS security. But earlier this week Steffen Ullrich, the maintainer of IO::Socket::SSL, released a new version of Net::SSLGlue that also allows for connecting to POP3 over TLS. And as opposed to many of the other modules, it also allows to verify the SSL certificate on the remote server for extra security. Net::SSLGlue works for Net::SMTP, Net::POP3, Net::LDAP, and LWP.
Here is an example of how you can connect to a POP3 mail server over TLS: