If you are planning to use SendGrid for sending newsletters or mass emails, go with "Pro" (starting at $90./month). The Pro level provides you with a dedicated IP address ascribed to your traffic.
Don't bother with "Essentials", you will be assigned a shared pool of IP addresses, and will be blocked because of questionable activity by previous users of same IPs.
Don't bother with "Essentials", you will be assigned a shared pool of IP addresses, and will be blocked because of questionable activity by previous users of same IPs.
BTW SendGrid Tech. Support are excellent.
(I am a customer, I'm not profiting from this).