My only issue in the last 2 years was with Gmail, which I eventually discovered on accident was apparently because of my lack of appropriate ipv6 records in my SPF tag.
I didn't catch it for a while because so much of the email world simply assumes ipv4, but traffic happily exits my ipv6 interface when the destination supports it.
I didn't catch it for a while because so much of the email world simply assumes ipv4, but traffic happily exits my ipv6 interface when the destination supports it.