We have noticed when we use reporting applications (event viewer capture, backup reports, etc) to send e-mail reports to and from Gmail accounts (or those controlled by Google Apps) we now get the warning message that “This message may not have been sent by…” even though we are sending on both ends. We understand why it happens, the reporting applications don't have the ability to use SSL for e-mail so we are stuck using the SMTP server our ISP provides which means Google never gets the DKIM signature they want on the e-mail that shows its coming from them. We don't have any e-mail accounts with our ISP and and to avoid confusion was just listing our normal Google controlled addresses in the to and from fields. Is there any concern getting this message from Google? The messages come through so far but want to make sure it won't eventually become blacklisted or anything. It seems the message only shows up in the Gmail interface, it doesn't come up in any e-mail clients accessing Google.
See this link for what we mean: http://mail.google.com/support/bin/answer.py?answer=185812