I have recently gone through an informative article that explains the detailed manual and a professional method to backup Gmail emails to hard drive. I tried the manual methods and it amazed me because the single article helped me to export Gmail emails to PST, MBOX, and PDF formats.

Apart from this, it also introduces the best Gmail Backup Software which is a comprehensive solution to backup and migrates Gmail items including emails, calendars, contacts, photos, etc. You can try its free demo version which allows you to analyze the performance of this advanced utility.