Fortunately we can forward every incoming mail to another account to make sure you receive all incoming emails easily. i.e: You have email A and B, and when someone send mail to email A, the mail will also forwarded to email B's inbox. So you can read the mail from email B without login to email A first.
And here's is how to do it:
1. Go to Your Gmail Settings > Forwarding and POP/IMAP > Click "Add a Forwarding Address" :
2. Enter Your Primary Email Address (the one that you want to forwarded to) :
3. Then Login to Your Email Account You Previously Added Above. And Check Your Inbox, You Should Receive Something Like A Pin. Copy and Paste It to The Box :
4. Click "Verify" and It's Done :
Not only Gmail accounts can be added to your forwarding list, but you can also add Yahoo!, HotMail, etc as well. Hope this useful for you. :)