[ Bcc'd to a contact at another large provider, which I hope will be the next one to top the list... No pressure Christian ... :-) ]
Just recently domeneshop.no have published DANE TLSA records for the MX hosts that support many of their hosted domains.
So today I count 102638 domains with correct DANE TLSA records for SMTP. As expected the bulk of the DANE domains are hosted the handful of DNS/hosting providers who've enabled DANE support in bulk for the domains they host. The top 10 MX host providers by domain count are:
42231 domeneshop.no 31928 transip.nl 15092 udmedia.de 1792 bhosted.nl 1262 nederhost.net 905 ec-elements.com 377 core-networks.de 290 uvt.nl 205 omc-mail.com 181 hot-chilli.net
The real numbers are surely larger, because I don't have access to the full zone data for any ccTLDs, and in particular .de and .nl.
There are 2113 unique zones in which the underlying MX hosts are found, this counts each of the above registrars as just one zone, so is a measure of the breadth of adoption in terms of servers deployed. Alternatively, a similar number is seen in the count (2219) of distinct MX host server certificates that support the same ~102000 domains.
Of the ~102000 domains, 539 have "partial" TLSA records, that cover only a subset of the MX hosts. While this protects traffic to some of the MX hosts, such domains are still vulnerable to the usual active attacks via the remaining MX hosts.
The number of domains with incorrect TLSA records or failure to advertise STARTTLS (even though TLSA records are published) stands at 85 (~30 are recent additions that will likely be resolved soon, the remaining ~50 are the long-term stable population of broken domains).
The number of domains with bad DNSSEC support is 414. The top 10 DNS providers (by broken domain count) are:
50 axc.nl 39 infracom.nl 24 registrar-servers.com 20 loopia.se 19 active24.cz 18 jsr-it.nl 16 forpsi.net 12 cas-com.net 8 is.nl 8 ignum.com
The number of domains that at some point were listed in Gmail's transparency report is 81 (this is my ad-hoc criterion for a domain being a large-enough actively used email domain). Of these 43 are in the most recent report:
gmx.at mail.de otvi.nl conjur.com.br posteo.de overheid.nl nic.br ruhr-uni-bochum.de xs4all.nl registro.br tum.de domeneshop.no gmx.ch uni-erlangen.de webcruitermail.no open.ch web.de debian.org gmx.com octopuce.fr freebsd.org mail.com comcast.net gentoo.org xfinity.com dd24.net ietf.org bund.de gmx.net netbsd.org fau.de hr-manager.net openssl.org gmx.de t-2.net samba.org jpberlin.de xs4all.net torproject.org kabelmail.de asp4all.nl lrz.de bhosted.nl