The email stated Pullar received a settlement in 2007 under an income protection policy. The Herald on Sunday understands it was more than $1 million.
Boag's email stated Pullar had been involved in a five-year battle against the insurance company that also involved allegations it had breached her privacy.
An ACC spokeswoman would not comment on Pullar's case. But in a statement on insurance payments, said: "Income protection payments are not considered earnings for the purposes of ACC weekly compensation and therefore aren't subject to abatement if a client receives both weekly compensation and income protection insurance.
"Income protection insurance can be used by clients, for example to top up their weekly compensation from 80 per cent to 100 per cent of pre-incapacity [earnings]."
Smith announced he was quitting his ministerial posts in an emotional speech this week.
It came after NZ First leader Winston Peters told Parliament it was "a shabby little case involving blackmail, sex, a minister with a conflict of interest".
But Vergne Wilson, whose ex-wife later married Smith, says the politician should not have resigned.
Wilson was married to Linley Newport for 10 years, before separating in 2005. The same year, Smith split from his wife of 20 years, Cyndy.
Smith and Newport's paths had crossed in 2004, through Smith's constituency work, and they became a couple a year after their separations. They married in 2009.
Wilson said he was disappointed to see Smith step down from his portfolios.
"It is sad that it has come to this because he has always acted with integrity and genuinely believes in what he's doing.
"He is passionate about his job. He's a hard-working guy and loves what he does."
The trio continued to have a great relationship and Wilson visited the children in Wellington when he could.
"It really upsets me that the family is going through this. It is a huge upset for them.
"My kids love him and he has genuine affection for them. If your wife was going to marry someone else, you couldn't pick a better guy or stepfather."