I have a TON of options at my disposal to help you here.
I've had 20 years of email automation experience using Azure, VB.Net, C#, PowerShell, VBA, SQL Server (yes there are TWO built in mail components in SQL Server) and DTS/SSIS and MS outlook.
Current iteration is a serverless function in Azure that handles email, text and robocalls if so desired.
I built a UI to enter email addresses or upload them in bulk for automated scheduled delivery with configurable messages.
Also have a PowerShell/Azure based version I'm using to email advertisements for Dental Practice out of Nevada.
Which ever option works for you, I can deliver it.