> The fact the source communicated with you using a non Gmail account is of minor importance
This is important to the story. If the source had communicated using their work (Google) email, then you could argue that Google hadn't accessed the reporter's Gmail account, but had instead invoked their (possible) employment agreement terms and read the Google employee's email. Without insider knowledge, no one could know for sure.
On the other hand, since the source used a non-Google email account, the only two possible ways that Google could know are: 1) if they read the reporter's emails or 2) if they have access to non-Google email services to read emails of arbitrary accounts.
Those aren't the only two possible ways Google could see non-Google email.
Was the source using a Google laptop? Was he or she using a Google network? Was the non-Google email service using SSL "several years ago" when this happened?
If the source used Google equipment and unencrypted email service, then the message is in plaintext on Google's network. No need to open Arrington's Gmail to read it.
The message passed in plaintext on the network. Were they sniffing and logging all traffic before the whistleblowing happened? Unlikely.
It's much more likely that they either 1) read Arrington's mailbox or 2) keylogged the crap out of the Google laptop the guy likely used. The latter method is not foolproof, whereas it's known that Google does have the capability to use the former. Occam would see 1 as the most realistic explanation.
The real question would be if Google logs all unencrypted email traffic across their networks. Otherwise, it would be hard to go back in time to see what was sent.
Hugely important. Even without any employment agreement terms, "employers probably [have] the legal right to read employee email messages sent using their equipment and network."
This is important to the story. If the source had communicated using their work (Google) email, then you could argue that Google hadn't accessed the reporter's Gmail account, but had instead invoked their (possible) employment agreement terms and read the Google employee's email. Without insider knowledge, no one could know for sure.
On the other hand, since the source used a non-Google email account, the only two possible ways that Google could know are: 1) if they read the reporter's emails or 2) if they have access to non-Google email services to read emails of arbitrary accounts.