Historically, email has been very easy to "spoof" and it has become increasingly difficult to send email from a website. By default, a CMS like Wordpress or Drupal will try to send email using a PHP script on the server. This means that the email "originates" from the web server's IP address, and depending on how your DNS settings are configured, those emails will either bounce, or end up in a spam folder.
The solution is to generally have the web site use an SMTP or API connection to a 3rd party transactional email service.
Your DNS records need to be updated accordingly, which may involve your IT department.
In no particular order:
- Mailgun
- Sendinblue*
- Mandrill (MailChimp)
- SendGrid*
- Amazon SES*
- SendLayer
- SMTP.com
- Postmark*
- SparkPost
- Zoho Mail SMTP*
*free plan available
Technically, these are not "transactional" - but should be mentioned:
