Andy Marshall is currently helping out at Colchester but is unlikely to be offered a permanent contract.
The experienced goalkeeper played 45 minutes for the Us in their 3-0 victory over Maldon & Tiptree in a pre-season friendly on Saturday.
He was able to be drafted in at short notice having been released by Aston Villa at the end of last season.
Colchester were only keen to bring him on board as short-term cover, though, while first-choice keeper Ben Williams is injured.
That means former Norwich and Ipswich shot-stopper Marshall can expect to be back on the market in the next few weeks.
Us boss John Ward has thanked the 35-year-old for helping him out, but admits he does not need to strengthen in the keeping department at present.
"We have Ben Williams who is not fit at the moment and I didn't want Mark Cousins to have to be playing and training every day," he said in the Green'Un.
"Andy was available and local to us, and we have had him come in and help us out until we get Ben fit.
"There is no promise of contracts, but he will benefit from training with us.
"I am not looking to bring him in as a third keeper, but it helps us out."