> Otherwise your local Toastmaster group is going to be a much more effective way to improve speaking skills.

This is probably accurate, but speaking skills are only part of presentation skills. A lot of what this group will help with is structuring proposals, structuring the actual presentation, working with talk reviewers, understanding CFPs, finding topics, finding audiences for topics, etc.

The mailing list can't help you with your enunciation, but it can help you turn a one paragraph thought into a structured outline.