If that's what the problem is, then that can easily be set with the
following Postfix setting without the need for customization scripts:
default_destination_recipient_limit = 1
Documentation for this setting is available at:
https://www.postfix.org/postconf.5.html#default_destination_recipient_
limit
It may also be helpful to adjust the delivery rate, which can also
be set in Postfix's "default_destination_rate_delay" setting (which
defaults to 0 seconds):
https://www.postfix.org/postconf.5.html#default_destination_rate_delay
(I don't know, off-hand, if other SMTP daemons have such settings.)
> I have nearly the exact same setup and usage you do. I got the same deferral
> when sending an email to <20 friends, of which about 15 were on Gmail.
> Exactly the same results as you got.
>
> Fortunately, I found I could schedule one recipient at a time (using
> opensmtpd) and each message went through without issue (I even scripted the
> last 10 or so and they all went through in <2s). Seems they don´t like small
> shops to send to more than one or two Gmail recipients at a time).
>
> I suppose I should send a similar message to my friends, and include my Gmail
> account, then see if then I can send the report in.
>
> Sean
>
> Typed with my thumb.
>
> > On Dec 30, 2023, at 05:01, Simon Wilson via mailop <mailop@mailop.org>
> > wrote:
> >
> > Thanks all. I'll answer comments here in one email.
> > I use a single mail host (mail.simonandkate.net) as MX for a range of
> > family domains on a fixed/business IP address through a high quality ISP
> > (not a variable IP, not in a dial-up block). I've had the same IP address
> > for about 7 years. It has a good reputation, sends < 1k emails per week,
> > and I monitor blocklists. Neither the domain nor the IP are on spamhaus or
> > other BLs. My parents' domain is howiesue.net, we've owned it for about 10
> > years. Its inbound MX and outbound SMTP host is mail.simonandkate.net,
> > which has a valid PTR associated with the IP address noted above (again,
> > which has been in place for many years).
> >
> > howiesue.net has a valid hard-fail/reject SPF policy for the IP mail host
> > we use, we DKIM sign all outbound messages with a 1024-bit key, and valid
> > DMARC is setup. I have the domain in Google Postmaster Tools, but is too
> > low volume to generate any data.
> >
> > I'll have a look at DNSWL.org - thank you Randolf for that suggestion.
> >
> > The error message from Google is specifically:
> >
> > 421-4.7.28 Gmail has detected an unusual rate of unsolicited mail
> > originating from your SPF domain [howiesue.net 35]. To protect our
> > users from spam, mail sent from your domain has been temporarily rate
> > limited. For more information, go to
> > https://support.google.com/mail/?p=UnsolicitedRateLimitError to review our
> > Bulk Email Senders Guidelines
> >
> > Google search tells me this is NOT the message they use when the IP address
> > is the issue, but that they are having some unknown issue with the domain.
> >
> > I've checked my logs, and the domain is not compromised; he's sent a total
> > of 10 emails in the last week lol... This one that Gmail have decided to
> > block is the first to Gmail this week, but he regularly sends to the people
> > on that list. The email contains 15 Gmail recipients, and is still deferred
> > 12 hours later.
> >
> > I've tested and they accept email from me to individuals on his list from
> > the same mail host from my personal domain - reinforcing that we don't have
> > an IP rep issue.
> >
> > Randolf - I've reviewed the Google support doc on deferred email, and there
> > is nothing in there that I need to change - we use TLS (with valid certs),
> > have valid PTRs and other DNS records, have SPF (with hard fail / reject
> > requested for non-authorised IPs) and DKIM, DMARC, and are not sending
> > spam, it's personal email not bulk. There is no reason on that page which I
> > can see which gives them reason to defer us.
> >
> > When I follow their troubleshooter, it drops me to the contact form Randolf
> > mentions, but I cannot achieve any progress because you *have* to include
> > "To help us investigate a message that was rejected or blocked, please
> > provide the full headers from a recent message (less than 12 days old)".
> > That header has to be from the RECEIVED end, i.e. Gmail - which I cannot do
> > because to do that I'd have to actually be able to get an email through
> > from the domain. I tried sending log details of the deferral with info on
> > our compliant setup, and the "ticket" is auto-closed because it doesn't
> > include the headers they "need".
> >
> > I think I'm just going to need to tell him to set up a different way to
> > contact his friends instead of this list...
> >
> > If I've missed something, I'd love to hear it.
> >
> > Simon
> >
> >
> >> On Saturday, December 30, 2023 20:28 AEST, Eduardo Díaz Comellas via
> >> mailop <mailop@mailop.org> wrote:
> >>
> >>
> > I've seen problems like this because of ISP listing large net locks as
> > "dialup" and not supposed to send email directly.
> >
> > Check spamhaus' PBL:
> >
> > https://www.spamhaus.org/pbl/
> >
> > Best regards
> >
> > El 30 de diciembre de 2023 7:40:59 CET, Simon Wilson via mailop
> > <mailop@mailop.org> escribió:
> >> I know, I'm not alone in this... :(
> >>
> >> I like to think that it's still feasible to run one's own email. I have
> >> for many years, and currently manage about a dozen email domains for
> >> family and friends. Most of the time all good.
> >>
> >> Then today my dad says to me "Why am I getting these bounce messages?"
> >>
> >> I check, and Gmail are deferring an email he sends every week to a group
> >> of friends, 20 all up, 15 of them on Gmail, saying his SPF domain is a
> >> source of unsolicited email (421-4.7.28). Outlook and Hotmail accept OK.
> >>
> >> This domain is old, not compromised, has SPF, DKIM (1024bit), DMARC, all
> >> valid. We send using TLS. We have correct PTR. His emails go out fully
> >> signed and pass checks. We don't send commercial emails, and that domain
> >> name is low volume and all emails individually written and sent through a
> >> webmail client, none of it is automated.
> >>
> >> Are we wasting time even trying any more?
> >>
> >> You can't even submit a request to them for help, because they ignore it
> >> unless you attach valid and current mis-classified headers from within
> >> gmail. Umm.. how can I do that when they're not accepting the email?
> >>
> >> Simon Wilson
> >> M: 0400 121 116
> >
> > --
> > Simon Wilson
> > M: 0400 121 116 _______________________________________________
> > mailop mailing list
> > mailop@mailop.org
> > https://list.mailop.org/listinfo/mailop
>
--
Postmaster - postmas...@inter-corporate.com
Randolf Richardson, CNA - rand...@inter-corporate.com
Inter-Corporate Computer & Network Services, Inc.
Vancouver, British Columbia, Canada
https://www.inter-corporate.com/
_______________________________________________
mailop mailing list
mailop@mailop.org
https://list.mailop.org/listinfo/mailop
