Nick Brooks, chair of the institute's standards committee and head of not-for-profit at accountancy firm Kingston Smith, will speak at the institute's direct marketing and fundraising conference in London.
Among the key issues will be the expected inclusion in the code of requirements that direct mail should not play on donors' feelings of guilt and that incentives put in mail packs should be relevant to a charity's cause.
Feelings in the sector ran high last year when a working party of direct marketing experts recommended that the code should ask fundraisers to curb their use of incentives such as pens and coins.
It also suggested monitoring the use of excessively emotional appeals and considering the environmental impact of direct mail (Third Sector, 9 November 2007).
"A direct mail pack aims to help people work with a charity to achieve change," said Mike Wade, head of central fundraising at WaterAid, who will join today's debate. "I don't think you need to use guilt to do that.
"In an ideal word, an incentive should be relevant to the cause and should help people understand what the issue is."
Alastair Irons, executive creative director, at direct marketing agency TW Cat, said: "I don't agree with the delivery of unsolicited gifts to try to prompt a response. I think the intention is to generate guilt."
But Stephen Pidgeon, chairman of the working party consulting on the new code, said guilt was inevitable.
"It's impossible to distinguish guilt from all the emotions that people feel when something wrong is going on, so ultimately guilt will feature," he said.
"There has been a ludicrous witch-hunt against incentives. I am adamantly opposed to expensive things such as umbrellas, but small incentives have a poignant message. I don't mind pens."
The institute's standards committee is currently considering the wording of the new code before passing it to trustees for final approval.