Not on my Bitfolk VPS, but I recently moved my main server to a
different company. The old one had no IP6 address, the new one has IP4
and IP6.
When I set up the spf for each of the domains hosted there, I put a typo in.
Instead of making the spf say
v=spf1 a mx ip6:nn00:nn98:nn:nn:0:0:0:1/64 -all
I made it
v=spf1 a mx ipv6:nn00:nn98:nn:nn:0:0:0:1/64 -all
They all have dmarc and dkim set up properly, but the effect of that
typo in the spf meant that the ip6 address was invalid, so Google
bounced all mail to gmail addresses, and various other emails just
weren't delivered.
As soon as I put the spf right, all was well.
--
Iain