You should consider moving your code out to leverage Azure Scheduler (http://www.windowsazure.com/en-us/services/scheduler/). This will be a more reliable scheduling service than using the above approach.
Reliable mail delivery will really only be via use of SendGrid - anything else is likely to get bounced by one blacklist or another. You can send up to 25,000 emails a month with SendGrid for free (http://sendgrid.com/windowsazure.html).
If you can't use SendGrid then you could use an SMTP relay outside of Azure (say, on your own network) that you can bounce mail through though even that may not work unless you modify the messages to remove the origin IP / hostname.