hello,

as always: imho (!)

but google/gmail is pretty open about why they deny your emails - idk ... mail authentication =?> dkim/spf/... or similar technical details etc.

interestingly i have more "problems" with the other "big" (free)mail providers like yahoo or gmx, which are often not so "open" about why they reject your mail ... even google is pretty happy with my setup :))

just my 0.02€