Review for MEGAbird by alberto.villar
Rated 5 out of 5 stars
I have been using this add-on during years (so with different versions of Thunderbird). I could always send 10-20 MB files perfectly.
I'm now using it to attach 300+MB files and I can say it performs as expected.
Very good and stable tool.
To create your own collections, you must have a Mozilla Add-ons account.