I’ve been using Thunderbird for a very long time. I love it. It’s one of my best friends, and it helps me get things done.

However, it doesn’t support some of the flashier stuff in OS X Lion and I would like to try and find an email client that’s more likely to. So I need your help in selecting a replacement. To aid you in giving me advice, here’s how I work with email and what features I certainly need in a new app:

• It must support bottom-posting by default. By this, I mean when I hit “Reply,” my cursor is placed, ready for bottom posting. (This is what has ruled out Mail.app in the past for me.)
• It must be able to send plain text emails without me having to fuss with anything. I want to be able to set one option and then not have to change anything ever again.
• It needs good search.
• It needs to be able to show me emails in a conversation view. Threaded would be awesome.
• It needs to be able to search within Thunderbird-created archive folders (or at least make it easy for me to understand how it archives).
• It needs to either already support or be likely to support Lion stuff in the future, such as full-screen use.

So here’s how I work with email: I run through my messages with a preview pane open, with one finger on the “delete” key and one finger on the “archive” key. If it’s an email I need to reference later, I archive it. (I don’t use folders. Everything goes into one archive and then I use search to find it if I need it later.)

If I’m not likely to need the information again, or if I can get the information from other sources, I will simply delete the email.

If an email needs a response, I reply to it right away using key shortcuts, then I archive it immediately. Once I’ve relayed the required information, it’s out of my inbox and out of my mind.

So that’s how I use email—any suggestions for a new client? I’m interested to hear what you have to say in the comments.