My pine config is still active and available but serves now only as a remote-in, or console bound backup mailer.
The first problem I encountered with t-bird is the helper apps. The list comes up blank from the installed freebsd port and there are no helper apps listed and no way to activate them. This was unlike pine where a url-viewer could be defined. With t-bird I discovered after much web digging if you have Freebsd/KDE/qt without gtk helper infrastructure, you'll need to define the url viewer for firefox. You do this under the advanced config editor, or in prefs.js:
For anything else, under pine/alpine you'd be editing your .mailcaprc, but under t-bird you'll need mimeTypes.rdf and Mime Edit. It was ridiculous how hard it was to find this functionality and for a long time I was hand editing the Mimetypes.rdf to add helper apps.