The answer to this is short: no. This is simply impossible. This is because with an A/B test you have 3 target groups:
The target group that gets variant A
The target group that gets variant B
The remaining target group that gets the winning variant
If in this situation, variant B wins, then your customers who receive variant A (the losing variant) will not receive variant B.
Your customer would otherwise receive an (almost) identical newsletter twice in one day. And that's not the intention.