Comment # 4 on bug 1093836 from Manfred Hollstein

(In reply to Andreas Stieger from comment #2)
> (In reply to Manfred Hollstein from comment #0)
> >   Enigmail: Error - no matching secret found to decrypt message
> 
> This is normally an indication of mixed used of GnuPG 2.0 and 2.2, e.g. as
> would happen when sharing a home directory, or when the gpg-agent keeps
> running.
> 
> > Downgrading to enigmail-1.9.9-9.1 results in a fully working
> > MozillaThunderbird/enigmail combination.
> 
> Hmm interesting.
> 
> > Since openSUSE Leap 15.0 already has enigmail-2.0.2 and gpg2-2.2, I booted
> > into Leap 15.0 to run the same test opening the exact same e-mail, and there
> > it works as expected.
> 
> Can you please cross-check you can decrypt the item with plain gpg 2.0 cli?

Yep, just saved the message to some new file "zoo", then ran "gpg2 --decrypt <
zoo" and saw everything being decrypted.