3.8.1 Setting in Gmail

Step 1 : In GMail, click at "Setting icon" and then "Settings"

Step 2 : Select tab "Forwarding and POP/IMAP"

Step 3 : To use POP3, Select "Enable POP for all mail (even mail that's already been downloaded)" in POP Download to ensure that your mail information will be downloaded completely, To use IMAP, Select Enable IMAP in IMAP Access

Step 4 : Click “Save Change”