"It was absolutely brilliant. There are congratulatory messages, cards of well done and good luck for the match against Bangladesh which is our World Cup final," McCallan told AFP ahead of Sunday's game with the Asian side.
The Irish vice-captain believes the team's success in reaching their maiden World Cup appearance has done wonders for Ireland cricket.
"I have been playing cricket for 11 years. It's a minority sport but what we have achieved in this World Cup is a great credit to Irish cricket and what it will do for Ireland cricket in the next ten years is phenomenal," said McCallan.
The 31-year-old said Ireland's first-round performance, during which they tied their game against Zimbabwe and registered a three-wicket upset win over Pakistan, has doubled cricket's interest.
"The huge amount of letters shows that fans now care for cricket and are taking a good interest in the game and we hope we cash in on it," said McCallan who will return to his job as a school teacher next week.
"We went through the letters all night and it was lovely. It gave us the feeling of success and rising interest."
Ireland, comprised mostly of amateur players, aim to beat Bangladesh in the hope of avoiding finishing at the foot of the Super Eights table.
"It's an important game and obviously we took a beating against Australia," said McCallan of Ireland's nine-wicket defeat here on Friday.
Australia, who sent Ireland in to bat, shot them out for a meagre 91 and wiped off the target off just 12.2 overs to finish the match before lunch.
"We have to hold our hands up sometimes and say that we were beaten by the world champions. We have put that behind us. We won't disrespect Bangladesh who are the next big team in the Super Eights.
"They have a good record and we have to play very very well. It is just like a Cup final for us and we know we can finish better if we win," said McCallan, whose team can also break into one-day international rankings with a victory.
According to the ICC (International Cricket Council) one-day rankings an associate team can get the 12th position if they beat two Test playing countries.
The current rankings of 11 teams is headed by defending World Cup champions Australia with Kenya in last place.