If you need to have for some reason more than one gmail account (ie. working for more companies) but you are checking just one mailbox regularly then below is the solution that might work for you as it did for me.

1. in the source gmail mailbox open settings (gear icon) and select see all settings and forwarding tab
2. add forwarding email, confirmation email should be sent to that mailbox, click the link and in new page accept the forwarding, also copy confirmation number
3. in source mailbox enter the confirmation number
4. select “forward a copy of incoming mail to” to your destination mailbox and also action that needs to be taken on every mail you will receive
5. in your destination email you can then create rules that will define the reaction on incoming (and forwarded email). For forwarded email create rule in “all settings” -> “filters and blocked addresses) tab create rule with matches -> from field enter the format: deliveredto: YOURSOURCE@EMAIL”

In that way, all incoming messages to your source email box will be redirected to the one you are actually checking and filtered with some additional action (like labeling).

Hope this short article can help.