Tool that allows you to view and extract attachments from email messages stored in Outlook PST files.

Reliable and easy-to-handle Gmail backup tool.
Free tool that allows you to convert and extract different types of files related to emails, calendars, contacts, and storage, compatible with major email clients.

Mozilla Thunderbird-based email client.
Email server with SMTP, POP3, virus protection and remote administration support.
Program that protects you from suspicious attachments, javascripts, etc.