Google released an updated version of Gmail this week which allow users to read their incoming mail into tabbed sections. One such section is the "Promotions" tab, which could mean that email marketing messages aren't getting into the main inbox, but rather a sub-folder in which marketing messages live. As Business Insider points out, this could mean that senders will see a drop in open rates when sending to contacts that use the Promotions tab. If this starts to happen, marketers could try to send plain text emails, which will be automatically sent to the mail inbox. These emails can advise contacts with a Gmail address to check their Promotions tabs for marketing messages.