Chrome: Corporate email systems often have ways of telling you if an email is read.

For users of Gmail in Chrome, MailTrack creates easy read receipts.

Note: If the recipient turns off automatic image loading, you won’t get a read receipt.

Just check sent items and a green checkmark will show when an email is read.

you might also receive email notifications when the email is read.

MailTrack| Chrome Web Store viaAddictiveTips