If you *must* use Gmail on WP, $5/month for Google Apps is an option.

I've migrated to Outlook.com. It has been okay but just barely good enough for my use. For example the folders and "category" combination can essentially do for me what "labels" did in Gmail -- but the filtering / rules in Outlook.com is severely lacking. It only allows *one* condition for each rule. No AND.. no OR for example. I've decided to go ahead and stay with Outlook.com for now but if it becomes unbearable I'm willing to dish out $60/year for proper Gmail, Contacts and Calendar syncing using Google Apps.

http://smb.gonegoogle.com/