Show encryption information what security does it provide?

rightclick contact -> show encryption information ->
prefer end to end encryption fingerprint

Let us presume, person A and B has verified the other person’s
fingerprint and they know they are correct. Then an
adversary cannot do a man in the middle attack? It does
not matter if he controls one or both of the email
accounts?
Thanks.

Let us presume, person A and B has verified the other person’s
fingerprint and they know they are correct. Then an
adversary cannot do a man in the middle attack?

if A and B use Verified Groups, this is correct, yes.

see https://countermitm.readthedocs.io/en/latest/new.html for backgrounds and detailed reasonings.