Clarification on Email Communication API call for sending Bulk Emails via Async and Sync!

When single Communication Email is sent from Fynd to Bulk Email IDs like to 1000 Email IDs in To, then

  1. Is there any limit around number of recipients which Fynd Communication API supports in To list, both in Async and Sync Communication API Call?
    Note:- RIL IDC Email SMTP server suggests best to have at max 300 email IDs supported by them in To.
  2. Is there any limitation on Attachment size which can be sent in Email?
  3. When delivery to certain Email recipients failed then how will Communication API notify about failure delivery ?

FDK JAVA API we are using for the same is
Async:-
@POST(“/service/platform/communication/v1.0/company/{company_id}/application/{application_id}/engine/send-async”)
Call<CommunicationPlatformModels.EngineResponse> sendCommunicationAsynchronously(@Path(“company_id”) String companyId, @Path(“application_id”) String applicationId, @Body CommunicationPlatformModels.EngineRequest payload, @HeaderMap Map<String, String> requestHeaders);

Sync:-
@POST(“/service/platform/communication/v1.0/company/{company_id}/application/{application_id}/engine/send-instant”)
Call<CommunicationPlatformModels.EngineResponse> sendCommunicationSynchronously(@Path(“company_id”) String companyId, @Path(“application_id”) String applicationId, @Body CommunicationPlatformModels.EngineRequest payload, @HeaderMap Map<String, String> requestHeaders);

As we discussed personally there is 25 mb of limit in attachment size while sending emails.

Thanks Suditya for confirming attachment size query point 2. Can you update on other queries as well.