Fabian Broghammer fired Rovers in front after just minutes, breaking clear of a square Shrimpers defence and shooting home at the second attempt after Paul Smith had saved his initial effort.
The visitors equalised five minutes before the break when Marc Laird's precise throughball allowed Gavin Tomlin to race clear and beat Neil Etheridge with his left foot.
Another left-footed finish from Kevan Hurst put Southend in front on the stroke of half-time and midway through the second half defender Ryan Cresswell made it 3-1, heading home a Hurst corner.
David Clarkson's 86th-minute penalty after a foul on Eliot Richards proved no more than a consolation for Rovers, who saw substitute Norburn given his marching orders moments later for a foul on Ryan Leonard.
