Dynamic switches allow you to tell blackhole how to respond to any given email.
For example, with default configuration blackhole will not delay while responding to clients and will blindly accept all email. Using dynamic switches, you can tell blackhole to bounce an email instead of accepting it or delay for 10 seconds before processing the email – without affecting any other emails you are sending to the service.
Blackhole has three response modes, you can find out more about what the modes are and the responses they send in the mode section.
Adding a dynamic mode switch header to an email message will make the blackhole service respond to the email using that response mode.
The X-Blackhole-Mode header is responsible for dynamic mode switching.
From: Test <test@test.com>
To: Test <test@test.com>
Subject: A test
X-Blackhole-Mode: bounce
This email will be bounced because of the X-Blackhole-Mode header.
From: Another Test <a.test@test.com>
To: Another Test <a.test@test.com>
Subject: A second test
X-Blackhole-Mode: accept
This email will be accepted because of the X-Blackhole-Mode header.
The X-Blackhole-Delay header is responsible for dynamic delay switching.
From: Test <test@test.com>
To: Test <test@test.com>
Subject: A test
X-Blackhole-Delay: 10
Blackhole will delay for 10 seconds before responding.
From: Test <test@test.com>
To: Test <test@test.com>
Subject: A test
X-Blackhole-Delay: 10, 60
Blackhole will delay for between 10 and 60 seconds before responding to
this email.
Because dynamic switches are just email headers, they can be combined.
From: Test <test@test.com>
To: Test <test@test.com>
Subject: A test
X-Blackhole-Mode: bounce
X-Blackhole-Delay: 10
Blackhole will delay for 10 seconds before bouncing this email.
From: Test <test@test.com>
To: Test <test@test.com>
Subject: A test
X-Blackhole-Mode: accept
X-Blackhole-Delay: 10, 30
Blackhole will delay for between 10 and 30 seconds before accepting
this email.