How many recipients should I include in my testing group?

There are no limitations when it comes to the right size of a testing group.
Of course, you should have enough people to send the message to and make
the test work, e.g. having 4 subscribers to test 5 messages wouldn’t
be possible.

To achieve statistically relevant information we recommend to have a group of
at least 250 recipients per tested message.

A handy slider will help you define how many recipients will get the A/B test
versions (and divide them into even testing segments automatically), and how
many will get the winning version. The test can be performed with up to 50%
of the selected recipients.