On 2023-03-24, Heiko Schlittermann via mailop <mailop@mailop.org> wrote:
> fh--- via mailop <mailop@mailop.org> (Fr 24 Mär 2023 03:56:53 CET):
>> > does anybody from mailgun read here?
>> > Your messages are tmprejected at our systems, w/o any chance to pass
>> > ever.
>> b/c they were sending spams?
>
> I can't tell, because we rejected them with 4xx and they do not pass the
> greylisting with a changing sender address.
I use the following snippets in my greylisting code, which pretty much
deals with the changing sender address problem, and also, partially,
the mail farm problem.
---
# to do greylisting sensibly on mail farms, we want to use
# the /24 of an IPv4 address, or the /48 of an IPv6 address
# try with ipv first
SENDER_HOST_PREFIX = ${if match{$sender_host_address}{:}{${mask:$sender_host_ad\
dress/48}}{${mask:$sender_host_address/24}}}
# also, because of all those sites that put a key into the sender address,
# if the localpart is longer than, say, 30 charactersm, we'll just replace
# it with a fixed string
SENDER_ADDRESS_COMPACTED = ${if >{${strlen:$sender_address_local_part}}{30} {ke\
yedsender@$sender_address_domain}{$sender_address}}
---
# and this is the normal greylist check
condition = ${readsocket{/var/run/greylistd/socket}\
{--grey \
SENDER_HOST_PREFIX \
SENDER_ADDRESS_COMPACTED \
$local_part@$domain}\
{5s}{}{false}}
---
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