Robert Koren doubled their advantage seven minutes before half-time and the margin of Albion's victory would have been much greater but for a Man of the Match display from Ipswich goalkeeper Richard Wright meant the score did not show the dominance than the home side showed.
Wright stood firm in the face of some fierce Albion pressure including saving a 74th minute penalty from Luke Moore after Tommy Smith had given the spot kick away.
While Wright kept the damage to a minimum the way that his side were cut apart is a major worry for Ipswich boss Roy Keane, who was taunted about his future by the Albion fans.
His side have picked up just one point from their opening four games and are leaking goals at an alarming rate, while not carrying much of a threat at the other end of the pitch.
Ipswich were fortunate to stay on level terms as long as they did. Wright did well to beat out Koren's fourth minute header, but was powerless to prevent Mulumbu opening the scoring.
Town looked to have escaped when David Wright cleared a Jonas Olsson header off the line following a Chris Brunt corner. But the ball flew invitingly to Mulumbu who made no mistake with a low 25-yard drive.
Ipswich continued to live dangerously with Wright denying Brunt and Moore before Albion turned their domination into a second goal. The lively Koren started and finished the move following a neat exchange with Chris Wood.
Koren rolled the ball into the path of the teenage New Zealand international, before taking a return pass and racing clear to beat Wright at his near post.
A two-goal interval lead was the least that Albion deserved and they would have taken an even more commanding advantage into half-time, had Wright not pulled off two more stunning saves to deny Koren and Wood.
To their credit, Ipswich did try and mount a second-half comeback.But Scott Carson dealt comfortably with a shot from substitute Alan Quinn and then twice frustrated Jon Walters.
Albion should then have gone on to record an even more emphatic win after Tommy Smith fouled Shaun Cummings to hand Albion their penalty.
But Moore's weak shot was palmed out by Wright and when the former Aston Villa striker tried to convert the rebound, he saw his follow-up effort cleared off the line by Alex Bruce.