Extensions now exist which offer Thunderbird users some of the rich extra functions provided by Mail.app plugins. Paolo Koasmos has written a collection of excellent extensions 
and Paul Tomlin’s Quick File gets close to the filing magic offered by Mail Act-on.
Paulo’s AttachmentRemember will catch messages to which you have forgotten to add attachments just like James Eagan’s missing attachments plugin.
Quick file by Paul Tomlin gives filing a tremendous speed boost over the “old drag ‘n’ drop”.
Select a message, hit a user-customizable hotkey (⌃Q works for me), and a dialog appears. Start to type and it offers a list of matching mailboxes that you can navigate through using the arrow keys. It’s quick.
Lastly, Paulo’s ExternalTemplateLoader brings MailTemplate to Thunderbird. It loads an external HTML file as the template for a message or a reply.
The one I use most wasn’t on the list, it’s called QuoteCollapse: https://addons.mozilla.org/thunderbird/347/ It hides the quoted part of the mail so you can skip it very easily but also unhide it with a simple mouse click.
Suggestion:
Would it be possible to develop a hack for Mail whereby, upon
invoking “Get Mail” , any mailbox with a new message opens up automatically? (Or does such a possibility already exist?)
This is how Eudora handles new mail, but I avoid Eudora because it does not support “Services”. I also do not use Rules because I have to open each mailbox to check my new mail. I would like Mail to do this automatically.
I would be willing to pay $25 for such a product.
Best regards,
Kim
@Richard – thanks for the tip. Sounds useful.
@Kim – I don’t know of anything that does this. The unread markers next to each Mailbox in the Mailbox Drawer are the closest thing.
Paulo’s AttachmentRemember sound like a great extension. Is there something like this for Mail.app?
Oups, really sorry. My first post and I got it all wrong. I later read about James Eagan’s missing attachments plugin….. Question answered! Once again, really sorry!