If you are one of many people or organizations in Canada which use Telus for your domain hosting provider and are interested in moving your email system to google apps gmail service, then you make note of the following.
Even after correctly setting up the MX service inside of the telus DNS web applet, you will need to give a call to Telus themselves and ask them to remove your domain from telus' internal sendmail list so that other people still using telus for the their email service will be able to send you emails.
Otherwise what happens is that when someone using the telus email system tries to email you, telus thinks that it already knows how to get ahold of you and sends the mail internally instead of properly resolving the the DNS information. Many emails will effectively disappear, or be bounced back noting that the user cannot be found.
You may as well ask for the shared hosting support number right off the bat, otherwise you may be explaining all this to deaf ears any number of times until you get someone who knows what you're gibbering about.
Please enjoy responsibly