Air Carrier E175 Captain reported encountering wake turbulence departing SEA in trail of an A321.

Narrative

Took off out of SEA behind an A321. After acceleration height and flap clean up; experienced wake turbulence. Plane dropped about 5 to10 ft.; causing people's possessions in the back to float away from them. When the aircraft began to bank from the wake turbulence; I took the controls from the First Officer and kept it from banking. I brought the aircraft back to straight and level and exited the wake turbulence by adding power. Upon landing; we received a master caution of ENG EXCEEDANCE. Maintenance Control informed me that it occurred a minute and a half after take-off; which is when the wake turbulence event occurred and the Engine Maintenance page on the MFD informed me that the number two engine experienced low oil pressure. During the wake turbulence event and recovery; no aircraft limit was exceeded. I spoke with the Duty Officer and was informed that a passenger has called customer service and said that the aircraft was 'out of control.' I assured the Duty Officer that at no point was the aircraft out of control. There were a few nervous fliers on board and I was informed by the Flight Attendants that the turbulence made their fear worse; so I am guessing it was one of them who called. The Duty Officer and I do not know what could have caused the low oil pressure. The aircraft was in control during the entire wake turbulence event.Recommend that SEA takes more time for wake turbulence avoidance in between take-offs. I learned to ask for two minutes behind an Airbus 321.