So if you have an user with email
firstname.lastname@example.org excluded from ban, and an user's email is the same, it will be detected by the way under spam list.
This problem will be resolved on 2.3.9, in the while, be sure that in phpBB your email or partial wildcards emails aren't on the excluded list!
Or you'll get:
on authenticating in WP, or coming as logged in phpBB to visit WP side.ERROR: wrong email or the provided username, email or IP address result banned on our forum.