Mail forwarded from Dreamhost isn't arriving

A friend sent an e-mail to my Dreamhost address this afternoon. I forwarded that e-mail to both my GMail and Yahoo accounts, but it never arrived at either account. I’ve checked the spam folders at both Yahoo and Gmail, but neither one contains the e-mail I forwarded to myself from Dreamhost. I’ve done this test at different times during the day, but it’s just not going through.

So far Dreamhost technical support has been good about checking into the issue and responding to my e-mails, so I’m not complaining about that. But I just thought I’d check here to see if anyone else has ever experienced a similar issue?

Are you forwarding from a script, an email client, or via “Also Forward” settings from within the Panel?

Email is forwarded unopposed to GMail accounts for me via homiemail-sub5 using ThunderBird, propagating the headers “References:” “In-Reply-To:” and “X-Forwarded-Message-Id:” correctly.