Developing an easy application in Java/Kotlin

I have a list of Discord servers operating in different countries and languages. The task involves sending private messages to users on the specified servers. The content of the campaign will be tailored to each server. A total of message variants have been prepared in 10 languages. Scope for Quotation Stage 1 - Test Sending 1000 test messages to check the effectiveness of the solution, the quality of execution, and the response of anti-spam systems. Stage 2 - Main Campaign Sending 10,000 messages per month for a period of 5 months. Total volume: 50,000 messages. Terms of Cooperation The contractor is responsible for the execution of the task from start to finish, including the preparation of the necessary infrastructure and accounts. On my side, I will provide: graphics, message content, list of servers, information on which language version should be used on a specific server. The order may be expanded if the test stage is successful and the messages effectively reach the recipients.