Jordan,
The 'error' you received on our site was really letting you know that you're subscribed to the post along with the title.. though there should have been a space:
You are now subscribed to the topic<TOPIC>
Your topic was "Could not instantiate mail function", so it came out as:
You are now subscribed to the topicCould not instantiate mail function
I think you'll likely get an email from this post I'm making
As for your issue, can you explain a bit more as to the flow of things? It sounds like:
* EasyDiscuss page is loaded
* A JFBConnect module (which one, JFBCLogin?) is loaded on this page
* User submits a post (I'm not familiar with this extension, just so you know)
* User is redirected to another EasyDiscuss page with the error message you noted
** If you setup the redirection to a non-EasyDiscuss page, it doesn't show the error?
I'm pretty clueless as to what could cause this, as JFBConnect doesn't do anything with mail settings on every page (just registrations or when a comment or like is submitted). My best suggestion is to try re-ordering the System (and maybe content plugins) to first or last in their respective groups. It's possible there's some weird conflict going on there.
If that doesn't help, can you post (or PM) a page this is happening on so we can see the code on the page and test what's happening?
Thanks,
Alex