With iOS, Mail can archive Gmail messages on your iPhone, iPad, and iPod touch. Archiving messages allows you to store messages you're done with but don't want to delete.
When you archive a Gmail message, it moves to the All Mail folder. Mail doesn't delete the message from your Gmail account.
When you use the Archive setting, it replaces all delete options, including tapping the Trash icon while you view a message, and selecting Edit to manage multiple messages.
To turn off Archive, go to Settings > Mail > Accounts > and tap your Gmail account. Then tap your Gmail account > Advanced and tap Deleted Mailbox under Move Discarded Messages Into.
Learn more about the Gmail archive feature in Gmail Help.
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