Currently, if a SWQL variable in an email returns multiple rows, only the first row will actually be displayed in the email. Tech Support have confirmed that this is the case.
For example, if we have a node that belongs to 2 applications, and run ${N=SWQL;M=SELECT DisplayName from Orion.APM.Application where NodeID = ${N=SwisEntity;M=NodeID}, it should return both applications - this would be useful when identifying what appes are impacted by a node outage/reboot etc.