"Hopefully you can all make it to celebrate."
In the email titled "4pm Friday", Mr Feeley also offered to provide more "bubbles to the mix" as the bottle of Gosset would not be enough for everyone.
Asked last night if a drinks function was appropriate, Mr Feeley said the investigation into Bridgecorp was one of the largest in the SFO's history and had demanded long hours and great commitment from the staff.
"At the conclusion of the project, it was appropriate to acknowledge the efforts of staff on this matter.
"In that particular case, it involved a modest number of drinks on a Friday evening in the SFO offices."
Asked how he came to have champagne belonging to Bridgecorp, Mr Feeley said the explanation was "quite simple".
His previous job was as chief executive of the Eden Park Redevelopment Board to raise the $240 million needed to revamp the stadium for the Rugby World Cup.
During the first six months of the Eden Park project, the redevelopment team worked in the former Bridgecorp headquarters.
"Three or four bottles of champagne were left behind after the sudden exit of the [Bridgecorp] directors following liquidation," Mr Feeley said.
"One bottle was kept with the expectation that it would be drunk at the conclusion of the project.
"I ended up at SFO before the completion of the project, and considered that - there being no better claimant to the bottle - it was not unreasonable to recognise the completion of a major investigation and the efforts of the staff with a drink.
"I would struggle to think that any reasonable person would consider a $70 bottle of wine an outlandish recognition.
"Equally, in the context of a $460 million failed company, I doubt that any reasonable person would take issue with the use to which the drink was put."
Bridgecorp was placed in receivership in July 2007, owing 14,500 investors almost $460 million.
Last month, receivers PricewaterhouseCoopers said secured debenture investors would be paid an interim dividend of 3.5c in the dollar. Total recoveries would be less than 10c in the dollar.
Mr Feeley was appointed SFO director in September 2009.
Of the seven SFO charges laid after the Bridgecorp investigation, five are against Petricevic and fellow director Robert Roest. Two are solely against Petricevic.
Both men have pleaded not guilty and will stand trial in March.
The SFO alleges Petricevic used Bridgecorp money to pay $1.2 million to a "sham" business run by a personal acquaintance, Janita Wright.
It says Ms Wright operated a business, ABb, that invoiced Bridgecorp for marketing consultancy work, database management, operation of an after-hours call centre and other business expenses.
But the work was allegedly either not done or the sums invoiced were out of proportion to the quality and quantity of the services provided and to Ms Wright's qualifications, skills and experience.
Announcing the charges in May last year, the SFO said the business was "in essence a sham to enable Mr Petricevic to make alleged fraudulent payments from Bridgecorp".
Petricevic and Roest have been charged over the purchase of the luxury vessel Medici.
It was allegedly bought and the operating costs paid with $1.8 million in Bridgecorp money but it was owned by Poseidon, a firm Petricevic directed and owned.
The seven charges involve a total of $5.2 million.
