Seek for Thunderbird ups your email functionality according to LifeHacker –
Thunderbird extension Seek adds advanced search and sort functionality to the open source email client, Thunderbird, through a feature called faceted browsing […] narrows down emails by a number of conditions, introducing tons of useful ways to slice and dice your inbox to find exactly what you want. Add to that the timeline feature, which looks like a blast along with being useful, and we’ve got a pretty worthwhile Thunderbird extension here…