Email can be a hazard when you're in the fast-and-furious discussion phase.
Then it's useful to have a F2F meeting (or conference, or whatever), with someone designated to take notes and post a summary. If there are conclusions drawn in the meeting -- and the meeting should be specifically scoped to do:
1. Reach a conclusion, or
2. Identify what additional information is required to accomplish 1, or
3. Determine that the problem is intractable
.. then those conclusions must be nailed down in writing immediately after. Bury your hatchets and grudges and get stuff done.
Then it's useful to have a F2F meeting (or conference, or whatever), with someone designated to take notes and post a summary. If there are conclusions drawn in the meeting -- and the meeting should be specifically scoped to do:
1. Reach a conclusion, or 2. Identify what additional information is required to accomplish 1, or 3. Determine that the problem is intractable
.. then those conclusions must be nailed down in writing immediately after. Bury your hatchets and grudges and get stuff done.