[Pacemaker] Avoiding an email flood with MailTo

[Dan Urist]

I have a 2-node cluster which runs several sets of vservers. Each set of
vservers is dependent on a different drbd volume. I would like to use
the MailTo agent to notify me when a resource fails over (either by
colocating an instance of the MailTo RA with each vserver and drbd
volume or including them together in a group), but if possible I would
like to constrain the MailTo agent so that if a drbd volume fails over,
I only get an email for that event and not a flood of emails for each
vserver that depends on that volume.