Spamhaus blocking Spectrum IPs; rbl_override not working

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Spamhaus blocking Spectrum IPs; rbl_override not working

Postfix Mail System

Sorry.. reposting with correct subject...


---------- Forwarded message ----------
Date: Tue, 21 Aug 2018 11:32:57 -0400 (EDT)
From: Fongaboo <[hidden email]>
To: Postfix users <[hidden email]>
Subject: Re: Spool directories on ext4 with encryption


Last night, it would appear that zen.spamhaus.org started blacklisting a number
of IPs assigned to Spectrum consumers, of which I am one.

When I tried telnetting to port 25 of my mail server and manually sending a
message to one of our virtual mailboxes, I got this error:

554 5.7.1 Service unavailable; Client host [<my-ip-address>] blocked using
zen.spamhaus.org


I tried putting a bunch of /8's that I know to be assigned to Spectrum, one of
which my own IP was definitely within, into rbl_override. I then ran postmap
rbl_override and restarted postfix.

No dice. Still got the error.

For the time being, I had to go into main.cf and comment out reference to
zen.spamhaus.org completely for now, but I would still prefer a more granular
solution.

BTW the smtpd_client_restrictions contains:

check_client_access hash:/usr/local/etc/postfix/rbl_override


This precedes all the reject references to specific blacklists.

I believe rbl_override has worked in the past. Any ideas why it's not working
in this case? This is what my Spectrum IP section looks like:

# Spectrum
23.0.0.0/8 OK
24.0.0.0/8 OK
50.0.0.0/8 OK
63.0.0.0/8 OK
64.0.0.0/8 OK
65.0.0.0/8 OK
66.0.0.0/8 OK
67.0.0.0/8 OK
68.0.0.0/8 OK
69.0.0.0/8 OK
70.0.0.0/8 OK
71.0.0.0/8 OK
72.0.0.0/8 OK
73.0.0.0/8 OK
74.0.0.0/8 OK
75.0.0.0/8 OK
76.0.0.0/8 OK
96.0.0.0/8 OK
97.0.0.0/8 OK
98.0.0.0/8 OK
99.0.0.0/8 OK
100.0.0.0/8 OK
104.0.0.0/8 OK
107.0.0.0/8 OK
108.0.0.0/8 OK
173.0.0.0/8 OK
174.0.0.0/8 OK
184.0.0.0/8 OK
199.0.0.0/8 OK
204.0.0.0/8 OK
205.0.0.0/8 OK
206.0.0.0/8 OK
207.0.0.0/8 OK
208.0.0.0/8 OK
209.0.0.0/8 OK
216.0.0.0/8 OK



TIA!
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Dominic Raferd


On Tue, 21 Aug 2018 at 16:43, Fongaboo <[hidden email]> wrote:

Sorry.. reposting with correct subject...

I tried putting a bunch of /8's that I know to be assigned to Spectrum, one of
which my own IP was definitely within, into rbl_override. I then ran postmap
rbl_override and restarted postfix.
 
No dice. Still got the error.

For the time being, I had to go into main.cf and comment out reference to
zen.spamhaus.org completely for now, but I would still prefer a more granular
solution.

BTW the smtpd_client_restrictions contains:

check_client_access hash:/usr/local/etc/postfix/rbl_override


This precedes all the reject references to specific blacklists.
I believe rbl_override has worked in the past. Any ideas why it's not working
in this case? This is what my Spectrum IP section looks like:

# Spectrum
23.0.0.0/8 OK
24.0.0.0/8 OK
...

I believe this format is not valid for hash tables, but you can use it for cidr tables:
check_client_access cidr:/usr/local/etc/postfix/rbl_override

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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Benny Pedersen-2
In reply to this post by Postfix Mail System
Change hash to cdir see mail archives Where i answered it kong time ago

Benny

On 21. august 2018 17.43.20 Fongaboo <[hidden email]> wrote:

> Sorry.. reposting with correct subject...
>
>
> ---------- Forwarded message ----------
> Date: Tue, 21 Aug 2018 11:32:57 -0400 (EDT)
> From: Fongaboo <[hidden email]>
> To: Postfix users <[hidden email]>
> Subject: Re: Spool directories on ext4 with encryption
>
>
> Last night, it would appear that zen.spamhaus.org started blacklisting a number
> of IPs assigned to Spectrum consumers, of which I am one.
>
> When I tried telnetting to port 25 of my mail server and manually sending a
> message to one of our virtual mailboxes, I got this error:
>
> 554 5.7.1 Service unavailable; Client host [<my-ip-address>] blocked using
> zen.spamhaus.org
>
>
> I tried putting a bunch of /8's that I know to be assigned to Spectrum, one of
> which my own IP was definitely within, into rbl_override. I then ran postmap
> rbl_override and restarted postfix.
>
> No dice. Still got the error.
>
> For the time being, I had to go into main.cf and comment out reference to
> zen.spamhaus.org completely for now, but I would still prefer a more granular
> solution.
>
> BTW the smtpd_client_restrictions contains:
>
> check_client_access hash:/usr/local/etc/postfix/rbl_override
>
>
> This precedes all the reject references to specific blacklists.
>
> I believe rbl_override has worked in the past. Any ideas why it's not working
> in this case? This is what my Spectrum IP section looks like:
>
> # Spectrum
> 23.0.0.0/8 OK
> 24.0.0.0/8 OK
> 50.0.0.0/8 OK
> 63.0.0.0/8 OK
> 64.0.0.0/8 OK
> 65.0.0.0/8 OK
> 66.0.0.0/8 OK
> 67.0.0.0/8 OK
> 68.0.0.0/8 OK
> 69.0.0.0/8 OK
> 70.0.0.0/8 OK
> 71.0.0.0/8 OK
> 72.0.0.0/8 OK
> 73.0.0.0/8 OK
> 74.0.0.0/8 OK
> 75.0.0.0/8 OK
> 76.0.0.0/8 OK
> 96.0.0.0/8 OK
> 97.0.0.0/8 OK
> 98.0.0.0/8 OK
> 99.0.0.0/8 OK
> 100.0.0.0/8 OK
> 104.0.0.0/8 OK
> 107.0.0.0/8 OK
> 108.0.0.0/8 OK
> 173.0.0.0/8 OK
> 174.0.0.0/8 OK
> 184.0.0.0/8 OK
> 199.0.0.0/8 OK
> 204.0.0.0/8 OK
> 205.0.0.0/8 OK
> 206.0.0.0/8 OK
> 207.0.0.0/8 OK
> 208.0.0.0/8 OK
> 209.0.0.0/8 OK
> 216.0.0.0/8 OK
>
>
>
> TIA!
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Postfix Mail System

Awesome! Thanks...


On Tue, 21 Aug 2018, Benny Pedersen wrote:

> Change hash to cdir see mail archives Where i answered it kong time ago
>
> Benny
>
> On 21. august 2018 17.43.20 Fongaboo <[hidden email]> wrote:
>
>> Sorry.. reposting with correct subject...
>>
>>
>> ---------- Forwarded message ----------
>> Date: Tue, 21 Aug 2018 11:32:57 -0400 (EDT)
>> From: Fongaboo <[hidden email]>
>> To: Postfix users <[hidden email]>
>> Subject: Re: Spool directories on ext4 with encryption
>>
>>
>> Last night, it would appear that zen.spamhaus.org started blacklisting a
>> number
>> of IPs assigned to Spectrum consumers, of which I am one.
>>
>> When I tried telnetting to port 25 of my mail server and manually sending a
>> message to one of our virtual mailboxes, I got this error:
>>
>> 554 5.7.1 Service unavailable; Client host [<my-ip-address>] blocked using
>> zen.spamhaus.org
>>
>>
>> I tried putting a bunch of /8's that I know to be assigned to Spectrum, one
>> of
>> which my own IP was definitely within, into rbl_override. I then ran
>> postmap
>> rbl_override and restarted postfix.
>>
>> No dice. Still got the error.
>>
>> For the time being, I had to go into main.cf and comment out reference to
>> zen.spamhaus.org completely for now, but I would still prefer a more
>> granular
>> solution.
>>
>> BTW the smtpd_client_restrictions contains:
>>
>> check_client_access hash:/usr/local/etc/postfix/rbl_override
>>
>>
>> This precedes all the reject references to specific blacklists.
>>
>> I believe rbl_override has worked in the past. Any ideas why it's not
>> working
>> in this case? This is what my Spectrum IP section looks like:
>>
>> # Spectrum
>> 23.0.0.0/8 OK
>> 24.0.0.0/8 OK
>> 50.0.0.0/8 OK
>> 63.0.0.0/8 OK
>> 64.0.0.0/8 OK
>> 65.0.0.0/8 OK
>> 66.0.0.0/8 OK
>> 67.0.0.0/8 OK
>> 68.0.0.0/8 OK
>> 69.0.0.0/8 OK
>> 70.0.0.0/8 OK
>> 71.0.0.0/8 OK
>> 72.0.0.0/8 OK
>> 73.0.0.0/8 OK
>> 74.0.0.0/8 OK
>> 75.0.0.0/8 OK
>> 76.0.0.0/8 OK
>> 96.0.0.0/8 OK
>> 97.0.0.0/8 OK
>> 98.0.0.0/8 OK
>> 99.0.0.0/8 OK
>> 100.0.0.0/8 OK
>> 104.0.0.0/8 OK
>> 107.0.0.0/8 OK
>> 108.0.0.0/8 OK
>> 173.0.0.0/8 OK
>> 174.0.0.0/8 OK
>> 184.0.0.0/8 OK
>> 199.0.0.0/8 OK
>> 204.0.0.0/8 OK
>> 205.0.0.0/8 OK
>> 206.0.0.0/8 OK
>> 207.0.0.0/8 OK
>> 208.0.0.0/8 OK
>> 209.0.0.0/8 OK
>> 216.0.0.0/8 OK
>>
>>
>>
>> TIA!
>
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Viktor Dukhovni


> On Aug 21, 2018, at 12:31 PM, Fongaboo <[hidden email]> wrote:
>
> Awesome! Thanks...

This is probably solving the wrong problem.  Instead of exempting
these IP ranges from RBL checks, exempt all authenticated submission
clients from RBL checks.  Use port 587 for submission.  Keep the
RBL checks on port 25.

--
        Viktor.

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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Matus UHLAR - fantomas
In reply to this post by Postfix Mail System
On 21.08.18 11:42, Fongaboo wrote:

>Last night, it would appear that zen.spamhaus.org started blacklisting
>a number of IPs assigned to Spectrum consumers, of which I am one.
>
>When I tried telnetting to port 25 of my mail server and manually
>sending a message to one of our virtual mailboxes, I got this error:
>
>554 5.7.1 Service unavailable; Client host [<my-ip-address>] blocked
>using zen.spamhaus.org
>
>
>I tried putting a bunch of /8's that I know to be assigned to
>Spectrum, one of which my own IP was definitely within, into
>rbl_override. I then ran postmap rbl_override and restarted postfix.

you have put half of the internet into your whitelist. Don't do that.
Viktor posted the correct hint: use authenticated SMTP on alternative ports.
End-users should not use SMTP on port 25.

># Spectrum
>23.0.0.0/8 OK

this is much more than just spectrum.

>24.0.0.0/8 OK
>50.0.0.0/8 OK
>63.0.0.0/8 OK
>64.0.0.0/8 OK
>65.0.0.0/8 OK
>66.0.0.0/8 OK
>67.0.0.0/8 OK
>68.0.0.0/8 OK
>69.0.0.0/8 OK
>70.0.0.0/8 OK
>71.0.0.0/8 OK
>72.0.0.0/8 OK
>73.0.0.0/8 OK
>74.0.0.0/8 OK
>75.0.0.0/8 OK
>76.0.0.0/8 OK
>96.0.0.0/8 OK
>97.0.0.0/8 OK
>98.0.0.0/8 OK
>99.0.0.0/8 OK
>100.0.0.0/8 OK
>104.0.0.0/8 OK
>107.0.0.0/8 OK
>108.0.0.0/8 OK
>173.0.0.0/8 OK
>174.0.0.0/8 OK
>184.0.0.0/8 OK
>199.0.0.0/8 OK
>204.0.0.0/8 OK
>205.0.0.0/8 OK
>206.0.0.0/8 OK
>207.0.0.0/8 OK
>208.0.0.0/8 OK
>209.0.0.0/8 OK
>216.0.0.0/8 OK

--
Matus UHLAR - fantomas, [hidden email] ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
WinError #99999: Out of error messages.
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Bill Cole-3
In reply to this post by Postfix Mail System
On 21 Aug 2018, at 11:42, Fongaboo wrote:
> I tried putting a bunch of /8's that I know to be assigned to
> Spectrum,
> one of which my own IP was definitely within, into rbl_override.
[...]

> This is what my Spectrum IP section looks like:
>
> # Spectrum
> 23.0.0.0/8 OK
> 24.0.0.0/8 OK
> 50.0.0.0/8 OK
> 63.0.0.0/8 OK
> 64.0.0.0/8 OK
> 65.0.0.0/8 OK
> 66.0.0.0/8 OK
> 67.0.0.0/8 OK
> 68.0.0.0/8 OK
> 69.0.0.0/8 OK
> 70.0.0.0/8 OK
> 71.0.0.0/8 OK
> 72.0.0.0/8 OK
> 73.0.0.0/8 OK
> 74.0.0.0/8 OK
> 75.0.0.0/8 OK
> 76.0.0.0/8 OK
> 96.0.0.0/8 OK
> 97.0.0.0/8 OK
> 98.0.0.0/8 OK
> 99.0.0.0/8 OK
> 100.0.0.0/8 OK
> 104.0.0.0/8 OK
> 107.0.0.0/8 OK
> 108.0.0.0/8 OK
> 173.0.0.0/8 OK
> 174.0.0.0/8 OK
> 184.0.0.0/8 OK
> 199.0.0.0/8 OK
> 204.0.0.0/8 OK
> 205.0.0.0/8 OK
> 206.0.0.0/8 OK
> 207.0.0.0/8 OK
> 208.0.0.0/8 OK
> 209.0.0.0/8 OK
> 216.0.0.0/8 OK

Apart from the hash/cidr issue and Viktor's point about having a
dedicated port 587 submission daemon instead of using port 25 SMTP for
submission, this list is ridiculous. It is far more than just Spectrum
and the arbitrary exemption of /8 blocks eliminates the point of using
DNSBLs at all.

I am guessing that since you didn't specifically say what type of
listing is causing trouble  but that it covers multiple Spectrum
addresses, it is probably a PBL listing. In many cases you can exempt a
single static address by yourself on the Spamhaus site. If that's not
possible for Spectrum space (i.e. because Spectrum wants that space
listed) you can still be more careful in your exemption by splitting up
your use of Zen by return code. So you could have:

smtpd_client_restrictions
     check_client_access cidr:/usr/local/etc/postfix/rbl_override
     reject_rbl_client zen.spamhaus.org=127.0.0.2,
     reject_rbl_client zen.spamhaus.org=127.0.0.3,
     reject_rbl_client zen.spamhaus.org=127.0.0.4,
     check_client_access cidr:/usr/local/etc/postfix/pbl_override
     reject_rbl_client zen.spamhaus.org=127.0.0.10,
     reject_rbl_client zen.spamhaus.org=127.0.0.11,

Where "rbl_override" is a list of CIDR ranges you want to exempt from
ALL classes of Zen listings, while "pbl_override" is a list of CIDR
ranges you want to exempt from just PBL listings.

Using a dedicated submission daemon for which you require encryption and
authentication is still the better solution, as you then do not need to
bother with any DNSBLs for submission OR overrides of any sort for
inbound transport.

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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Postfix Mail System
In reply to this post by Viktor Dukhovni

Very good. As long as 'permit_sasl_authenticated' is way at the top of the
list, this should do that?

On Tue, 21 Aug 2018, Viktor Dukhovni wrote:

>>
>> On Aug 21, 2018, at 12:31 PM, Fongaboo <[hidden email]> wrote:
>>
>> Awesome! Thanks...
>
> This is probably solving the wrong problem.  Instead of exempting
> these IP ranges from RBL checks, exempt all authenticated submission
> clients from RBL checks.  Use port 587 for submission.  Keep the
> RBL checks on port 25.
>
> --
> Viktor.
>
>
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Viktor Dukhovni


> On Aug 21, 2018, at 1:31 PM, Fongaboo <[hidden email]> wrote:
>
> Very good. As long as 'permit_sasl_authenticated' is way at the top of the list, this should do that?

This is mostly the wrong question.  You might for example want to use
"postscreen" at some point, which does not do SASL.

Instead of whitelisting your way around the RBLs, use a dedicated
submission service which never uses RBLs, but *requires* TLS and
client authentication.  In that context, "permit_sasl_authenticated"
is not so much "at the top" as the entirety of the access control:

  submission inet n       -       n       -       -       smtpd
    -o syslog_name=postfix/submission
    -o smtpd_tls_security_level=encrypt
    -o smtpd_sasl_auth_enable=yes
    -o smtpd_tls_auth_only=yes
    -o smtpd_reject_unlisted_recipient=no
    -o smtpd_client_restrictions=$mua_client_restrictions
    -o smtpd_helo_restrictions=$mua_helo_restrictions
    -o smtpd_sender_restrictions=$mua_sender_restrictions
    -o smtpd_recipient_restrictions=
    -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
    #                           --------------------------------
    -o milter_macro_daemon_name=ORIGINATING

--
        Viktor.

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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Postfix Mail System
In reply to this post by Bill Cole-3


On Tue, 21 Aug 2018, Bill Cole wrote:

> smtpd_client_restrictions
>    check_client_access cidr:/usr/local/etc/postfix/rbl_override
>    reject_rbl_client zen.spamhaus.org=127.0.0.2,
>    reject_rbl_client zen.spamhaus.org=127.0.0.3,
>    reject_rbl_client zen.spamhaus.org=127.0.0.4,
>    check_client_access cidr:/usr/local/etc/postfix/pbl_override
>    reject_rbl_client zen.spamhaus.org=127.0.0.10,
>    reject_rbl_client zen.spamhaus.org=127.0.0.11,

That's pretty neat. Are those IP's on the end ones to be specifically
*rejected*? Can CIDR format be used?

Also should the last two lines start with reject_pbl_client?
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RE: Spamhaus blocking Spectrum IPs; rbl_override not working

Fazzina, Angelo
Hi, they are return codes.

https://www.spamhaus.org/news/article/713/changes-in-spamhaus-dbl-dnsbl-return-codes


-ANGELO FAZZINA

ITS Service Manager:
Spam and Virus Prevention
Mass Mailing
G Suite/Gmail

[hidden email]
University of Connecticut,  ITS, SSG, Server Systems
860-486-9075

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Fongaboo
Sent: Tuesday, August 21, 2018 1:51 PM
To: Postfix users <[hidden email]>
Subject: Re: Spamhaus blocking Spectrum IPs; rbl_override not working



On Tue, 21 Aug 2018, Bill Cole wrote:

> smtpd_client_restrictions
>    check_client_access cidr:/usr/local/etc/postfix/rbl_override
>    reject_rbl_client zen.spamhaus.org=127.0.0.2,
>    reject_rbl_client zen.spamhaus.org=127.0.0.3,
>    reject_rbl_client zen.spamhaus.org=127.0.0.4,
>    check_client_access cidr:/usr/local/etc/postfix/pbl_override
>    reject_rbl_client zen.spamhaus.org=127.0.0.10,
>    reject_rbl_client zen.spamhaus.org=127.0.0.11,

That's pretty neat. Are those IP's on the end ones to be specifically
*rejected*? Can CIDR format be used?

Also should the last two lines start with reject_pbl_client?
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Viktor Dukhovni
In reply to this post by Postfix Mail System


> On Aug 21, 2018, at 1:51 PM, Fongaboo <[hidden email]> wrote:
>
> That's pretty neat. Are those IP's on the end ones to be specifically *rejected*? Can CIDR format be used?

Instead of making this up, you could look at the documentation:

   http://www.postfix.org/postconf.5.html#reject_rbl_client

> Also should the last two lines start with reject_pbl_client?

Instead of making this up, you could look at the documentation:

   http://www.postfix.org/postconf.5.html#smtpd_client_restrictions

--
        Viktor.

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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Postfix Mail System

Yeah some of the links shared in between our correspondence set me on the
right path. I got it now. Thanks everyone!

On Tue, 21 Aug 2018, Viktor Dukhovni wrote:

>
>
>> On Aug 21, 2018, at 1:51 PM, Fongaboo <[hidden email]> wrote:
>>
>> That's pretty neat. Are those IP's on the end ones to be specifically *rejected*? Can CIDR format be used?
>
> Instead of making this up, you could look at the documentation:
>
>   http://www.postfix.org/postconf.5.html#reject_rbl_client
>
>> Also should the last two lines start with reject_pbl_client?
>
> Instead of making this up, you could look at the documentation:
>
>   http://www.postfix.org/postconf.5.html#smtpd_client_restrictions
>
> --
> Viktor.
>
>
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

Bill Cole-3
In reply to this post by Postfix Mail System
On 21 Aug 2018, at 13:51, Fongaboo wrote:

> On Tue, 21 Aug 2018, Bill Cole wrote:
>
>> smtpd_client_restrictions
>>    check_client_access cidr:/usr/local/etc/postfix/rbl_override
>>    reject_rbl_client zen.spamhaus.org=127.0.0.2,
>>    reject_rbl_client zen.spamhaus.org=127.0.0.3,
>>    reject_rbl_client zen.spamhaus.org=127.0.0.4,
>>    check_client_access cidr:/usr/local/etc/postfix/pbl_override
>>    reject_rbl_client zen.spamhaus.org=127.0.0.10,
>>    reject_rbl_client zen.spamhaus.org=127.0.0.11,
>
> That's pretty neat. Are those IP's on the end ones to be specifically
> *rejected*?

No, those are specific Spamhaus ZEN return codes. See
https://www.spamhaus.org/zen/ for their specific meanings.

> Can CIDR format be used?

For DNSBL return codes? No. If I am interpreting the postconf(5) man
page correctly, the above could be consolidated like this:


smtpd_client_restrictions
    check_client_access cidr:/usr/local/etc/postfix/rbl_override
    reject_rbl_client zen.spamhaus.org=[127.0.0.2..4],
    check_client_access cidr:/usr/local/etc/postfix/pbl_override
    reject_rbl_client zen.spamhaus.org=[127.0.0.10;127.0.0.11],

However I may be misinterpreting the range & list syntax described
there...

> Also should the last two lines start with reject_pbl_client?

No. See the postconf(5) man page, where reject_rbl_client is documented.
The name "reject_rbl_client" is an historical artifact of the first
DNSBL (the MAPS RBL) having its name  genericized in the Postfix feature
name. That feature is used for all DNSBLs, which is why it needs a base
domain argument with an optional return code.
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Re: Spamhaus blocking Spectrum IPs; rbl_override not working

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> On Aug 21, 2018, at 11:42 AM, Fongaboo <[hidden email]> wrote:
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>
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> Last night, it would appear that zen.spamhaus.org started blacklisting a number of IPs assigned to Spectrum consumers, of which I am one.

[…]

> # Spectrum
> 23.0.0.0/8 OK
> 24.0.0.0/8 OK

[…]

OT, but is your list of exemptions reflective of what spamhaus is blocking?  I see a number of chunks of address space in there that are used for Spectrum Business (TWC Business) in NYC.  That service is sold as allowing basic server hosting (including email).  This seems a bit broad...

>
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> TIA!