He said he can't turn off Gmail sync because he needs it to sync with Lotus Notes.
He claims that even though he's turned off email notifications it's still chirping every time he gets an email. I just tested mine and it definitely goes silent with notifications turned off.
Which creates a question of my own: Is there a way to get the green LED and the status bar notification when you get an email, but not make any sound?
I guess one solution would be to create a sound file that's just silence and assign that as the email ringtone.
Open the GMail app. Press the "menu" key. Tap "settings." Scroll down to where it says "Notification Settings." The first box, labeled "E-Mail notifications," will enable the notification LED for when new e-mail arrives. The 2nd option in this subheading is to choose your e-mail notification ringtone. Open that and choose "silent." This will turn off e-mail alert ringtones SPECIFICALLY for this GMail user account. If he has more than one GMail account associated with his phone, he must do this for EACH account.
Also, if he has any e-mail accounts that aren't GMail (e.g., Yahoo! Mail, Exchange, etc.) that he checks through the E-Mail app, he can do the same with all these accounts.
AFAIK, without disabling GMail sync, there is no way to set check frequency for gmail to "never" as it works through push notification. It doesn't really "check" for e-mail unless the server receives one, at which point it will push it to your phone and notify you. The only checking it does is syncing your account with older e-mails that are already in the inbox or refreshing your inbox if you've checked/received/sent e-mails through other methods.