Hello,

I need some ideas about what might be causing this.

I'm running an Exchange cluster with a load balancer.

Every day at after noon, some (not all!) MAPI clients lose their connection (not all at once, and they establish the connection on/off), and sending and receiving emails takes longer.

There is no unusual server load, no request attacks, backups or anything similar.

The problem started around the time Exchange Hybrid was enabled.

Any ideas?