Origin of the myth
There is a misconception on the internet that services like Constant Contact,
Mailing List Services Reduce Deliverability
In fact, using any of those services increases the chance that your E-mails will be blacklisted. All E-mail server operators know that those services are used exclusively for sending out E-mail marketing material. Sendgrid has a very poor reputation for handling
This means if your business uses one of these services you could be blacklisted even if you never send out spam. Simply associating with these spam giants will cause you reduced deliverability.
Your Business E-mail should be 100% private.
There’s No Such Thing As Free Services
Many open source software applications are free, but internet services are not. Anyone who offers “Free service” is doing so as a marketing trick so they can eventually turn you into a paying customer, at best. And chances are they are getting value from your patronage in other ways even while you use their “free” plan.