Heho, hm, not sure. Looking at the 'email-security-scans.org' data, fcrdns is at ~95.5% of senders. For comparison:
DKIM: ~55.2% SPF & Valid: ~91.0% TLS: ~96.0% Greylisting (attempting to resend): ~97.4% IPv4: ~97.9% IPv6 (sending): 56.2% IPv6 (sending+auth DNS+rec DNS): ~35.7% So even though that sample is a bit biased, i'd say that fcrDNS is more 'lived practice' than SPF. ;-) With best regards, Tobias On Tue, 2023-05-09 at 11:40 -0700, Michael Peddemors via mailop wrote: > Hi Laura, > > I think we have to disagree here. The PTR naming is set via > SendGrid. > It doesn't NEED to be the same as the A record. This is for those > MTA's > that do forward/reverse matching, which isn't always successful. > > Yes, doing that for a IPv6 email address to satisfy Google, go ahead. > > But nothing wrong with sending an email from a PTR with a name, that > doens't have the FQDN forward/reverse matched. > > As long as there is a URL associated with the domain name. > > eg. http://mileageplus.com (Redirect to UA site URL) > > Perfect forward/reverse FQDN matching is still a little aggressive > IMHO, > and especially problematic. Some people think they need 20 PTR > records, > one for each A record.. (No, that is worse) > > Postfix does allow forward/reverse checking, I would NOT enable that > for > the IPv4 space (yet) > > On 2023-05-09 10:22, Laura Atkins via mailop wrote: > > That’s a Sendgrid IP, they likely told UA to put in a DNS record, > > but UA > > never did. ¯\_(ツ)_/¯ n > > > > > On 9 May 2023, at 18:01, Stephen Frost via mailop > > > <mailop@mailop.org> > > > wrote: > > > > > > Greetings, > > > > > > I'm getting some inbound email attempts that I believe are > > > legitimate > > > from United Airlines that are being rejected due to: > > > > > > May 9 12:55:38 tamriel postfix/smtpd[1221960]: warning: hostname > > > o1.email.smallbusiness.mileageplus.com does not resolve to > > > address > > > 50.31.61.242 > > > > > > Tracking this back, near as I can tell, postfix is correct here > > > in that > > > 50.31.61.242 / 242.61.31.50.in-addr.arpa resolves to > > > o1.email.smallbusiness.mileageplus.com but > > > o1.email.smallbusiness.mileageplus.com doesn't seem to actually > > > exist: > > > > > > dig o1.email.smallbusiness.mileageplus.com a > > > > > > ;o1.email.smallbusiness.mileageplus.com.IN A > > > > > > ;; AUTHORITY SECTION: > > > smallbusiness.mileageplus.com. 600 INSOA > > > vndcdf-fs0000-gma3-vip.ual.com. ualipconfig.united.com. 40 10800 > > > 3600 > > > 2592000 600 > > > > > > Hopefully someone on here is from UA or knows how to get in touch > > > with > > > someone there who could like into fixing that. > > > > > > Thanks, > > > > > > Stephen > > > _______________________________________________ > > > mailop mailing list > > > mailop@mailop.org > > > https://list.mailop.org/listinfo/mailop > > > > -- > > The Delivery Experts > > > > Laura Atkins > > Word to the Wise > > la...@wordtothewise.com > > > > Email Delivery Blog: http://wordtothewise.com/blog > > > > > > > > > > > > > > > > _______________________________________________ > > mailop mailing list > > mailop@mailop.org > > https://list.mailop.org/listinfo/mailop > > _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
