PostGrid has been great for automating our insurance mails for our client
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Postalytics - Automated direct mail software that’s faster, smarter & better. Postalytics sends personalized direct mail from your CRM and analyzes delivery & response.
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Lob - A simple API to integrate print & mail solutions into your applications.
SendGrid - Learn why more developers choose SendGrid for their email deliverability service to send transactional emails triggered by web apps. Get started for free
AmazingMail - Business print-mail solution