3rd-party services to handle email sending

Here are a couple of good links which discuss the relative merits of different 3rd-party services to handle email sending:

• http://stackoverflow.com/questions/4798141/sendgrid-vs-postmark-vs-amazon-ses-and-other-email-smtp-api-providers
• http://stackoverflow.com/questions/3746213/sendgrid-vs-postmark/3830175