There are many email service providers that allow you to route email through their systems.
The main benefits of these providers include:
- Tracking of email delivery
- Possible inclusion in various whitelisting/trusted-sender programs (e.g. ReturnPath)
- The vendors use the various feedback and notification loops at the major ISPs to address spam complaints.
- They track bounce rates and provide you with stats.
- Turn-key implementation of SPF/DKIM and similar email technologies that may improve email delivery rates.
You can certain do all of this by sending from your own server; however, that would require a lot of setup.
Most importantly is that the third party provide you the reporting tools you need. For example, I don't think Amazon's SES provides the same level of statistics, whitelist inclusion and other features that others provide.
Different Channels for Different Emails
More importantly, you need to segment your email based on its purpose/contents. I generally recommend the email buckets:
Transactional email would automated/semi-automated notices often sent from a computer to a person. Password resets, shipping notifications and similar emails.
Marketing emails are just that. Newsletters, special offers, mailing lists, etc. These are often to sent to people that have weak affiliation with your business/organization.
Business/personal emails are sent from a person to a person. These are often the most valuable emails - think of a sales discussion.
I recommend you use different email channels for all of these. Of these, never mix your marketing emails with the other two.
If you use a third party email service provider, then consider setting up different delivery channels for each type of email. This is pretty easily done if you:
- Use hosted email for Business/Personal correspondence
- Use a email marketing service for your marketing efforts
- Use a 3rd party provider or your server for your website emails.
For example, a mix of Hosted Exchange, MailChimp (or similar), and Sendgrid (or similar) would give you three unique channels for each type of email.
The benefit of this approach is that your most valuable email (person to person) is in its own channel and the likelihood of your business/personal correspondence being disrupted by a run-away cron job or marketing email blast is limited.