Foden was released by England earlier this week, but will play no part in Saints’ Premiership game against Gloucester on Saturday, at the request of the RFU.
The full-back has started the past 10 Northampton games after recovering from the ankle ligament damage sustained at Bath in September, which kept him out for 10 matches.
He has yet to return to peak form, only showing glimpses of being back to his best in wins against Exeter, on January 5, and Gloucester two weeks ago.
And Mallinder said: “I probably wouldn’t say he’s 100 per cent match fit.
“He’s had a serious injury which kept him out for a long time and he’s probably not been as we would have liked and as Ben would have liked, but he’s getting there.
“We’ve just got to be careful what we do with him in the week, he can’t over-train, but he will get there. We’ll look after him.
“He’s working hard on it. We saw glimpses of it last week, he made a couple of line breaks, that he made look fast and I’m sure he’s not a long way off getting back to the Ben Foden of old.”
Mallinder, speaking at Wednesday’s press gathering, didn’t feel it would be long before Foden forced his way back into the England squad.
And he felt it was good for club and country that the 27-year-old would return to Saints with a point to prove.
But Foden will be deprived of a chance to impress this weekend, thanks to the RFU’s eagerness to see him rested.
“In terms of England, they’ve got good players and they’re playing well,” said Mallinder on Wednesday.
“Ben Foden’s been out and he’s got to justify his place. What Stuart Lancaster has done (releasing Foden), I don’t think anyone can argue with.
“What every player’s got to do is play well for the club. If they are outstanding for their club, they’ve got a very good chance of being picked for the international team.
“Ben is not far off and we know what he’s capable of. One or two really good performances in a Saints shirt should see him, quite rightly, put back in that England team.”