how many PM's may one store?

[languagelounger]

I keep getting a message that our thread is storing too many PMs. Have deleted about 120 (rough guess) but still getting the message. Please could you advise how many is too many? With thanks for your helpful EDF service.

[languagelounger]

Doh! Have just seen the answer, below. Pls excuse, I am a bit slow today. And yesterday, come to think of it. Then there was Monday, and yes, wasn't too sharp at the weekend either. Shoot me now.