I am a bit out of my league in understanding this fully, but I get the gist of it.
I have a Domain name registered with another registrar. I forward the aliased emails to other email accounts.
The registrar's mail forwarding system does NOT rewrite the mail header. Therefore my redirected email is often rejected based on a SPF mismatches. "Mail header rewriting" is on their todo list and will be implemented in the future.
Can you recommend a domain registration service that already tackles this problem? Will transferring my current domain and renewal to that registrar help me? Does DreamHost correct this issue?