Evolution is the messaging component of GnomeOffice, a full fledged suite running on the Gnome platform. Add-ons are built-in and to me looks to require a new download for new features.
Thunderbird is the Mozilla Foundation's premier email application that can have extended features via add-in's in a framework that makes it possible to even be compatible with Firefox.
Part of work actually requires some monitoring of URLs in spammed emails and I was looking to bridge a gap between office spam and the volume of spam being received in several personal spam honeypots.
Thanks to being able to setup multiple accounts on Microsoft Outlook its possible to just move all received spam into a separate account folder via a rule -- in theory. Right now I've not gotten down to fully doing this as due to the amount of list mails I do receive in my work mail its just easier to monitor the Spam and Junk folder before manually moving to an IMAP shared folder.
Enter Search Filters.
I've been using Thunderbird for some time and have gotten used to its quirks on the Windows platform (ie. storage limitation or errors) so having this run on Kubuntu was not too bad. In fact I noticed some speed increase and stability moving back to the original intended Linux platform. As for Evolution, this is somewhat new to me and I've done some really light tinkering with earlier versions.
The race however is the ability to script and automate as well as how better (how many buttons and clicks) it is to get a filter in place and start to search for "finds" (ie. bot links, phishing, droppers, etc.). Apparently though Thunderbird's extension provides for making quick filters, its message indexing speed is slow. Note I am basically "grepping" more than 30k worth of spam at any one time accumulated over the years. Evolution's performance surprisingly is a bit better in terms of displaying found messages and though limited add-ons makes it a more stable platform to do queries. In short, damn!
More food for thought as I immerse myself more into the Linux world that this Macbook Pro am typing on runs beautifully and expensively...