If you just want to backup your Gmail account, maybe should you have a look at this post.
It's about the Backup Gmail script.
You can also set up automated incremental backups if i'm right (haven't personally tested it).
Usage: backup_gmail.py backup_dir email@address password
Options:
-h, --help show this help message and exit
-r, --restore Restore backup to online gmail account
-i, --inc Use incremental backup
-k, --keep_status Keep the mail read status (Slow)
-s START_DATE, --start=START_DATE
Backup mail starting from this date. Format:
30-Jan-2010
-e END_DATE, --end=END_DATE
Backup mail until to this date Format: 30-Jan-2010
--include=INCLUDE_LABELS
Only backup these labels. Separate labels by '^'
Format: label1^label2
--exclude=EXCLUDE_LABELS
Do not backup these labels. If --include is used this
flag will be ignored. Separate labels by '^' Format:
label1^label2
-c CONFIG_FILE, --config=CONFIG_FILE
Load setting from config file
-p PROFILE, --profile=PROFILE
Use this profile in the config file.