Re: [exim] Getting duplicate deliveries with redirect router

On 26/11/2020 09:06, Gedalya via Exim-users wrote:
>> When user1 sends a message to user2 and user3, and user3 also gets generated *twice* by a redirect router, user3 ends up getting the message twice.
>>
>
>> bcc:
>>   debug_print = "R: bcc for $local_part@$domain"
>>   driver = redirect
>>   data = ${lookup{$local_part}lsearch{CONFDIR/bcc}}
>>   verify = false
>>   unseen = true
>>   repeat_use = false

> Is it the fact that the same address is generated separately as a child address of two recipients?

That's the basic cause. The "unseen" probably wasn't helping.
Exim tries it's best to track the chain of generated addresses, and de-duplicate - but
there are situations it doesn't deal with. You are better off using a redirect
with data of "original + additional", for your case of adding a bcc.

It's still vulnerable to cases when user2 and user3 couldn't be handled during
the same delivery run. You'd have to invoke one-time-only routing to solve that -
discarding the reasoning for having the re-route-on-every-deliver-try that is
normal behaviour.

> Can someone please help and explain, is this a bug, or am I misunderstanding something?

It's a problem with your expectations.
--
Cheers,
Jeremy