Archived - iPhone: About Gmail and Recent Mode
This article applies to iPhone Software 1.1.2 or earlier, which used POP as the default Gmail setting. With iPhone Software 1.1.3 or later, Gmail uses IMAP and there is no Recent Mode feature and there isn't a 30 day limit of Gmail viewable on iPhone.
Gmail is one of the email services that work with iPhone.
When sending Gmail from iPhone, the sent message will show up as a new message in your iPhone Inbox as if you have cc'ed yourself. If you don't want this behavior, try turning "Use Recent Mode" off.
Also note that only the last 30 days worth of Gmail will be viewable on iPhone. If you have an unread message older than 30 days that you want to read, try turning "Use Recent Mode" off.
To turn Recent Mode off, tap Settings > Mail > Your Gmail account name > Advanced, and turn off "Use Recent Mode."
For more information on Recent Mode, see this Gmail Help Center article:
Configuring your email client: iPhone
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