On Fri, Sep 28, 2012 at 11:00:08AM -0700, Jeff Green wrote: > The change should not be noticeable, but the most likely problem > would be legitimate @wikimedia.org mail being treated as spam. If > you hear of this happening please let me know. Anyone who sends all mail marked as "from"[1] their @wikimedia.org address through Gmail's SMTP server, through an SMTP server hosted by Wikimedia (is there one?), or through any other server identified in the SPF record should be fine. And anyone who isn't sending "from" an @wikimedia.org address should be entirely unaffected. If anyone is sending mail marked as "from" their @wikimedia.org address through some other SMTP server (e.g. through their home ISP), they might start to see trouble with this change and likely will when the SPF record is changed to ~all. Also, any recipient who has their mail forwarded might have trouble *receiving* messages from @wikimedia.org addresses, unless their forwarding service takes SPF into account or their destination mailbox doesn't check SPF. OTOH, these people would have the same problem with receiving mail from all the other domains that currently implement SPF. [1]: There are actually two concepts of "from" involved in email. The first, the "envelope sender" or "mail from", is the address that bounce notifications should be sent to. The second is the address that actually shows up as "From:" in the email message. SPF is intended to target only the former, but SenderID hijacks the SPF specification to also test the latter.