The T-Mobile Sidekick® fetches e-mail from integrated (POP3 / IMAP) accounts every 30 minutes, unless there is unread e-mail on the server. As long as new unread e-mail sits on the server, the Sidekick automatically fetches every 15 minutes. When no new e-mail is found, the delay period is reset to 30 minutes.
Force fetch POP or IMAP account immediately
From the Email application, press Menu + U.
Force fetch @tmail.com e-mail immediately
From the Email application, press Menu + Shift + S.