Youngster Stake Claim for Place on Sunday
Tommy Smith came on as a sub with just over 20 minutes to go, in his return from a broken ankle.
It was 4-1 at half-time to the Blues thanks to Ronan Murray and Reggie Lambe both grabbing a brace, John Herd for the Shrimpers.
Lambe got another two before the final half hour, Murray adding Ipswich's seventh in between two more Southend goals.
With the East Anglian derby coming up on Sunday, the youngsters will surely have caught the eye of manager Jim Magilton - or not.