The Saints emerged victorious at Sandy Park as they outscored their hosts by three tries to one to move back into the top four.
Mallinder said: "This win was important because it has put us back in to the mix and with the next four games being non-league, in terms of Heineken Cup and the LV=Cup, it leaves us in a decent position.
"But you want to be in the top four come the end of the season so I can still see that there is going to be a lot of changes before then. But it is good preparation for us before the our Heineken Cup tie against Castres Olympique.
"The win away to Ulster [before Christmas] has put us back on track but it is going to be difficult in the Heineken Cup but it has given us something to play for. What we need to do is focus on our home form.
"We have had some cracking wins away - we have won down here, we have won at Gloucester and at Bath as well as away at Ulster - but what we need to do is get back our home form so next week will be a good test."
The Saints lost skipper Dylan Hartley to the sin-bin just before half-time and during the England hooker's 10-minute absence they conceded three penalties but also pulled one back before being restored to full strength.
Mallinder added: "It was an important period and I think what you can't do is sit back and do nothing.
"I think in the past we have been guilty, when down to 14 men, of just sitting back too much.
"It is always tough to come to Exeter and they have a very good record, and quite rightly so.
"They are a good team and they test your defence, put you under pressure by playing a lot but I thought our defence was really good.
"We were up for it and we took our opportunities well. We have a decent record here and we have had some tough games to win here including last season's match which determined who went in to the play-offs.
"You have to play well here to win and you have to put them under pressure and make them make mistakes. We haven't been playing that badly recently and we came close to beating Saracens last week."
Exeter head coach Rob Baxter said: "I don't think we were far off winning the game.
"It wouldn't have taken any more physical endeavour from us, it would have just taken a little more mental sharpness and a little better control of certain parts of the game.
"You are always disappointed when you lose a game but the bigger disappointment was that we were in it for large parts but I am not sure that we appreciated the pressure that we probably had on Northampton for large periods of the game.
"Northampton had a three or four-point lead on a number of occasions with plenty of time on the clock.
"We were the team that was playing and being able to control possession for periods but we almost played until we made the error.
"What we are striving for is being able to flick that switch from being that team that wants to attack, wants to be ambitious, hunting to keep possession and breakdown the opposition but also looks up and sees that there is a decision to be made and makes the right one.
"That has always been the battle for us since we came in to the Premiership.
"Becoming that complete side is what it is all about and I just think that Northampton did better than us in this game."
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