We use Google Apps for our domain email, so we have a support@***.ca
If you're using WHMCS,
Setup > General settings > Mail tab. Set the "Mail type" to SMTP and use the Gmail SMTP settings. All your email from WHMCS will now go through Gmail's SMTP servers, including order confirmations, invoices etc.
The downside is that everything will be sent from 1 email address, so if you have multiple departments for your support set up, no matter which department you're sending from, all mail will go through that 1 email address.