I'd like to restrict SMTP login for certain users to my Exchange 2010 servers. I've been looking at the receive connectors, but I can't find a way to remove the "Exchange Users" role from specific accounts. Anyone know of a way to do this?
Why are you wanting to do this? What are you trying to accomplish?
If you are wanting to prevent them from sending but still allow receiving you can just crank down their send limit.
In the mailbox properties, Mailbox Settings, Storage Quotas.
Uncheck the "use mailbox database defaults"
Set the "Prohibit Send" to something like 1MB.
That will prevent them from sending out email but they'll still be able to receive.