[Custom SMTP Email Server] - Outlook365 Error - 432 4.3.2 Concurrent connections limit exceeded.
As of 2024, Outlook365 users may encounter the error "432 4.3.2 Concurrent connections limit exceeded" when sending batch emails due to a new limit of three simultaneous connections. Additionally, throttling limits include sending 30 messages per minute and a daily recipient cap of 10,000, with excesses resulting in delivery delays or errors. For more details, visit the provided Microsoft resource link.