From Newsgroup: comp.mail.sendmail

All,
I run a small mail server that relays two domains via uucp, and one
domain as forward to a telus.com address, which these days is handled by
gmail infrastucture.

The forwarded domain has been inundated with UCE for a while. Gmail will
reject those mails (rightfully so), which leaves me with double bounces
for the mails with forged sender addresses.

My question: How can I set up Sendmail so that it will not accept
incoming mail (bonus: for a specified domain) until downstream has
accepted the forward?

I have tried

define(`confDELIVERY_MODE', `interactive')

but that doesn't have the desired effect.

Cheerio,
Hauke
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From Newsgroup: comp.mail.sendmail

Hauke Fath wrote:

My question: How can I set up Sendmail so that it will not accept
incoming mail (bonus: for a specified domain) until downstream has
accepted the forward?

Compile with -D_FFR_PROXY and try DeliveryMode=s
Note: it only works for a single RCPT and there might
be other restrictions.

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From Newsgroup: comp.mail.sendmail

Claus A#mann wrote:

Compile with -D_FFR_PROXY and try DeliveryMode=s

Is that equivalent to the m4 define(`confDELIVERY_MODE', `interactive')?

Note: it only works for a single RCPT and there might
be other restrictions.

Ominous... I'll give it a spin.

Cheerio,
Hauke
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From Newsgroup: comp.mail.sendmail

According to Hauke Fath <hauke@Espresso.Rhein-Neckar.DE>:

All,
I run a small mail server that relays two domains via uucp, and one
domain as forward to a telus.com address, which these days is handled by >gmail infrastucture.

The forwarded domain has been inundated with UCE for a while. Gmail will >reject those mails (rightfully so), which leaves me with double bounces
for the mails with forged sender addresses.

My question: How can I set up Sendmail so that it will not accept
incoming mail (bonus: for a specified domain) until downstream has
accepted the forward?

Having been around this barn a few times, I have found that the only thing
that works reliably is to deliver to a local mailbox, and set the Gmail account to retrieve the mail using POP. If the user wants, it's not too hard also to configure the gmail account to send mail from the forwarded address with the outgoing through your server so the DKIM and SPF are right.
--
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly
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From Newsgroup: comp.mail.sendmail

Hauke Fath <hauke+usenet@causeuse.org> wrote:

Claus A|fmann wrote:

Compile with -D_FFR_PROXY and try DeliveryMode=s

Is that equivalent to the m4 define(`confDELIVERY_MODE', `interactive')?

In short: No.

I just checked out the 8.19.0.1 source and found the following in daemon.c:

case 'D': /* DeliveryMode */
switch (*v)
{
case SM_QUEUE:
case SM_DEFER:
case SM_DELIVER:
case SM_FORK:
#if _FFR_PROXY
case SM_PROXY_REQ:
#endif

and this is in:

sendmail/sendmail.h:# define SM_PROXY_REQ 's' /* synchronous mode requested */

So 'i' stands for 'interactive' DeliveryMode while 's'
stands for 'synchronous'.

br,
KK
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From Newsgroup: comp.mail.sendmail

Kalevi Kolttonen <kalevi@kolttonen.fi> wrote:

Hauke Fath <hauke+usenet@causeuse.org> wrote:

Claus A#mann wrote:

Compile with -D_FFR_PROXY and try DeliveryMode=s

Is that equivalent to the m4 define(`confDELIVERY_MODE', `interactive')?

In short: No. [...]

Thanks for checking. :)

Cheerio,
Hauke
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From Newsgroup: comp.mail.sendmail

John Levine <johnl@taugh.com> wrote:

My question: How can I set up Sendmail so that it will not accept
incoming mail (bonus: for a specified domain) until downstream has
accepted the forward?

Having been around this barn a few times, I have found that the only thing that works reliably

In what sense? I haven't had complaints from the user, so would assume
that the mail he expects to get does in fact reach him. We did observe
that his proper Gmail account has more aggressive filtering of forwarded
mail than his legacy Telus account I forward to.

My current problem is the swamped postmaster account. While I can (and
do) filter the double bounces into a separate mailbox to be discarded wholesale, I am worried about false positives.

is to deliver to a local mailbox, and set the Gmail account
to retrieve the mail using POP.

The mail server does not deliver locally. It forwards my own mail
domains via uucp, and the guest domain to Telus/Gmail.

Cheerio,
Hauke
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From Newsgroup: comp.mail.sendmail

According to Hauke Fath <hauke@Espresso.Rhein-Neckar.DE>:

John Levine <johnl@taugh.com> wrote:

My question: How can I set up Sendmail so that it will not accept
incoming mail (bonus: for a specified domain) until downstream has
accepted the forward?

Having been around this barn a few times, I have found that the only thing >> that works reliably

In what sense? I haven't had complaints from the user, so would assume
that the mail he expects to get does in fact reach him. We did observe
that his proper Gmail account has more aggressive filtering of forwarded
mail than his legacy Telus account I forward to.

They reject a lot of perfectly good mail, particularly mail that came
from Gmail or other google hosted domains.

If your user hasn't noticed that mail is disapperaing, great, but I'm surprised. Mine sure did.
--
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly
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From Newsgroup: comp.mail.sendmail

John Levine <johnl@taugh.com> writes:

If your user hasn't noticed that mail is disapperaing, great, but I'm surprised. Mine sure did.

And they still continue to use gmail? Why? Do they thibk it was an
accident? Or an error on your side?


Bj|+rn
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From Newsgroup: comp.mail.sendmail

On 12.05.2026 08:07 Bj|+rn Mork wrote:

John Levine <johnl@taugh.com> writes:

If your user hasn't noticed that mail is disapperaing, great, but
I'm surprised. Mine sure did.

And they still continue to use gmail? Why? Do they thibk it was an accident? Or an error on your side?

They do not know about the issues of it and if someone tells them, the
issue is somewhere else for them, as GMail "works" for them.
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From Newsgroup: comp.mail.sendmail

Marco Moock <mm@dorfdsl.de> writes:

On 12.05.2026 08:07 Bj|+rn Mork wrote:

John Levine <johnl@taugh.com> writes:

If your user hasn't noticed that mail is disapperaing, great, but
I'm surprised. Mine sure did.

And they still continue to use gmail? Why? Do they thibk it was an
accident? Or an error on your side?

They do not know about the issues of it and if someone tells them, the
issue is somewhere else for them, as GMail "works" for them.

Yes. But if it "works" then there is nothing to complain about, is
there?


Bj|+rn
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From Newsgroup: comp.mail.sendmail

Bj|+rn Mork <bjorn@mork.no> wrote:

Marco Moock <mm@dorfdsl.de> writes:

On 12.05.2026 08:07 Bj|+rn Mork wrote:

John Levine <johnl@taugh.com> writes:

If your user hasn't noticed that mail is disapperaing, great, but
I'm surprised. Mine sure did.

And they still continue to use gmail? Why? Do they thibk it was an
accident? Or an error on your side?

They do not know about the issues of it and if someone tells them, the
issue is somewhere else for them, as GMail "works" for them.

Yes. But if it "works" then there is nothing to complain about, is
there?

Most people care about silently vanishing messages.

br,
KK
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From Newsgroup: comp.mail.sendmail

kalevi@kolttonen.fi (Kalevi Kolttonen) writes:

Bj|+rn Mork <bjorn@mork.no> wrote:

Marco Moock <mm@dorfdsl.de> writes:

On 12.05.2026 08:07 Bj|+rn Mork wrote:

John Levine <johnl@taugh.com> writes:

If your user hasn't noticed that mail is disapperaing, great, but
I'm surprised. Mine sure did.

And they still continue to use gmail? Why? Do they thibk it was an
accident? Or an error on your side?

They do not know about the issues of it and if someone tells them, the
issue is somewhere else for them, as GMail "works" for them.

Yes. But if it "works" then there is nothing to complain about, is
there?

Most people care about silently vanishing messages.

Sure, we can certainly hope so. But the context is gmail users, not
most people.

Gmail users can either be happy that gmail "works" for them, or they can
stop using gmail. There are no other alternatives. Specifically: There
is nothing other mail admins can do to fix gmail. Gmail is tuned
towards agressive spam filtering with a high false positive rate, and it
scores sender domains based on mail volume.


Bj|+rn
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