"Their boards saw an individual who met their expectations of a good chairperson, regardless of their family situation. I hope our board can be as open minded," said the email, seeking backing in her bid to become chair.
Today Schwaner, who is married to Botany MP Jami-Lee Ross, would not say who questioned her ability to chair the board with two young children.
"Those who brought it up know who they are," she said.
Collings could not be reached today for comment on the issue.
In her resignation letter, Schwaner alleged that under the chairmanship of Collings in the past term, the board had become a "toxic environment" and a culture had developed of attacking council employess.
"He is unprofessional, he is a poor leader and he has fixed views on issues," she said.
"I have no confidence in the leadership of the Howick Local Board," Schwaner said in the letter to council chief executive Stephen Town.
Last night, Collings said Schwaner walked out after the board voted in favour of him serving a second term as chairman.
He said her decision was "disappointing" and a surprise given they both stood on the Vision and Voice ticket.
In response to her allegations, he said: "I'm not going to lower myself to that level. I've got the support of the community and I've got support from the board." He denied a culture existed of attacking council staff.
A council spokeswoman said Schwaner's resignation had been received and a byelection would be held in the Botany subdivision of the Howick Local Board.
The spokeswoman said a byelection could not occur before February 17 and it was too early to confirm a date and the likely cost.