If you want to send emails later or we say schedule them in Gmail than Right Inbox can do this work easily. Well Right Inbox is a just an extension which when installed and permitted can be embed into your Gmail account and can be used to schedule your emails right away. This can be helpful if you wanna send some occasion greetings or any other stuff or a particular day but you might not be available for writing that email down than you can schedule it now and let Right Inbox deliver it for you when ever you want it to be.
If you want to install Right Inbox and schedule your emails, than you can visit there there installation page to get extension and follow all the steps to authenticate it with your Google account. So now just send all the greetings right away without actually being there sitting and typing for them :)