This doesn't look like it's email originating from your system. Instead, it looks like spamdyke has accepted the message and then qmail is doing the rejection. My guess is that it passes through spamdyke with an invalid destination user. Qmail then tries to reject it.

You can avoid this by adding invalid user checks in spamdyke so it doesn't reach qmail by setting "recipient-validation-command=<program>" (I use spamdyke-qrv) and "reject-recipient=invalid".


On 11/07/2016 10:59 AM, BC via spamdyke-users wrote:

It hasn't risen to the level of DDOS, yet, but I'm getting many hundreds of these messages per night (and it is now continuing during the day).

They look like this:


Hi. This is the qmail-send program at
I tried to deliver a bounce message to this address, but the bounce bounced!

<>: does not like recipient.
Remote host said: 550 5.1.1<>: Recipient address rejected:
Giving up on

--- Below this line is the original bounce.


... each one with totally unrelated email and IP addresses and with variable sizes and all in MIME format.

I use FreeBSD here. Running qmail in a jail. I do use ssmtp running on the host (not jailed) in order to get the periodic daily/weekly/monthly reports.

Is someone somehow using my system to try to send spam?

Any idea how to block this?

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