If you are looking for best Gmail Backup Tool than I will recommend you to use the MacSonik Gmail Backup Tool for Mac. It helps to remove duplicate mail items on the basis of To, From, Date, Subject, Bcc, Body, etc. The software is capable to backup and migrate all messages from Gmail account into 18+ file formats. Using this tool users can backup Gmail account email attachments in a separate folder.This tool helps you to backup of Gmail mailboxes into different file formats  like PST, PDF, MBOX, EML, MSG, etc on Mac .  The software gives you an option of Advanced Filter Option for Selective Email Backup which helps users to backup Google email account emails selectively.  It is 100% safe and virus free that provides a secure backup of Google Mail emails.