I have three clients on spork, I know two are having difficulties. the third has not contacted me about any mail issues. UPDATE: the third client just called and cannot receive or send emails. All three cannot receive or send emails.
Webmail seems to work, as does the forwarders I have set up for them to other email addys.
I did set up my own dreamhost email account on their computers, to see if it was their system, but that worked. So, it seems to only be on spork accounts these clients are on.
I am sending in a support ticket on this now.