Re: Email hosting;

Hi Parlesstwo,

According to your description, my understanding is that you would like to use both Office 365 and Google mail with one domain like @contoso.com.

If yes, you can achieve this goal by using the Simple Domain Sharing for SMTP Email Addresses.
To do this, you can refer to the article below:
http://community.office365.com/en-us/wikis/exchange/simple-domain-sharing-for-smtp-email-addresses.aspx

Thanks,
Wilfred Ying