Could you please add Thunderbird support? In theory, it shouldn't be that hard to adapt the Firefox plugin. I've been setting up email servers using DANE/TLSA records for awhile now, and when I use Let's Encrypt certificates, Thunderbird tends to complain. Regardless of the CA issue, I like the idea of a DANE validator which ensures I'm always connecting to the correct SMTP/IMAP server - instead of having Thunderbird accept any cert it finds signed by a CA in its bundle. Thanks.