I sent someone a message and it was returned with the error "Failed SPF".

This happens if you're sending mail from your Boreal email address, but are using another provider's mail server.  The SPF system verifies your email address and mail server, and if you're not sending Boreal email via Boreal's servers, it assumes this is a spammer spoofing your email address and may block the message.

To fix this, make sure your outgoing mail server is set to mail.boreal.org or smtp.boreal.org, and that you have SMTP Auth turned on, per the directions shown on this page.