Besides being my favourite mail program, Mozilla Thunderbird is totally free of charge, and has a nifty junkmail filter built in!
* Automated update to streamline product upgrades. Notification of an update is more prominent, and updates to Thunderbird may now be half a megabyte or smaller. Updating extensions has also improved.
* Spell check as you type.
* Built in phishing detector to help protect users against email scams.
* Podcasting and other RSS Improvements.
* Deleting attachments from messages.
* Integration with server side spam filtering.
* Reply and forward actions for message filters.
* Kerberos Authentication.
* Auto save as draft for mail composition.
* Improvements to product usability including redesigned options UI, and SMTP server management.
* Many security enhancements