I am working on Salesforce App where there is a custom object named Distributor (Distributor__c). A distributor has primary email address as one of the fields. When a new distributor record is added an email is suppose to go out welcoming them to the service with some other information (So on a bulk insert using dataloader, mass emails would be sent). Similarly, the user can send mass email notification to all the distributors (using a custom vf page and UI).
My problem is, I cannot use Salesforce's Messaging.MassEmailMessage since it wont work with custom objects and custom email templates. Neither can I use SingleEmailMessage since even if I put all the distributor email addresses in a list and email them, they can all see each others email addresses which is something the client does not want.
What I am looking for is a single email service that can also handle bulk. I came across SendGrid and MailChimp which provide mass email services. I would like your opinion on which one is better and can work smoothly with Salesforce. Or if there is another native solution without using these third party email service providers.
Appreciate the help.