On 01/06/2023 21:37, Julian Bradfield via Exim-users wrote:
In response to the recent RCPT-flooding attacks, I changed my
acl_check_rcpt verification check to say:
deny
domains = +local_domains
!local_parts = postmaster
!verify = recipient
message = Unknown user
delay = 5s
When I test non-existent addresses with a dummy smtp session using
exim -bh
then I see the delay being applied:
check delay = 5s
delay modifier requests 5-second delay
delay skipped in -bh checking mode
However, in the exim log file I'm still seeing 99 denied RCPT commands
all with the same timestamp.
How can this be?
acl_check_rcpt's deny applies to the RCPT not the connection. This is
like if there is one non-existent recipient in a batch then only that is
denied and the rest are delivered. In your case it tests 99 and denies 99.
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