Town had lost their two previous Championship games but became the first side this season to deny the leaders a goal in the league.
Mackay preferred to focus on Ipswich's upward curve since Mick McCarthy took charge in November, saying: "We were playing against a team who are right at the top of the form table with a new manager and some new players.
"They'd only lost two in 10 so if we had not worked as hard as them then we'd have been beaten.
"For us to come out with another clean sheet, our fourth in five games, on the back of 13 points out of 15, I'm delighted.
"I think you can always hope you can create more chances. We created 20 attempts on their goal but it is the clinical nature of that final pass that was missing.
"The conditions were pretty poor in terms of the wind and the rain and I think both sides struggled with that at times."