You can set the options in NIMCustomMessageConfig used to specify whether the message history is stored on the servert and whether messages are roaming.

For more information, see NIMCustomMessageConfig.

The following is an example where messages are not stored on the server and are not delivered as roaming messages, and multi-device synchronization is not required:

dart// Test account
String account = 'testAccount';
// P2P chat
NIMSessionType sessionType = NIMSessionType.p2p;
String text = 'this is an example';
// Custom message configuration
NIMCustomMessageConfig config =
    NIMCustomMessageConfig(enableHistory: false,
    enableRoaming:false,
    enableSelfSync:false);
// Send the message
Future<NIMResult<NIMMessage>> result = MessageBuilder.createTextMessage(
    sessionId: account, sessionType: sessionType, text: text)
    .then((value) {
    if (value.isSuccess) {
    value.data!.config = config;
    return NimCore.instance.messageService
        .sendMessage(message: value.data!, resend: false);
    } else {
    return Future.value(value);
    }
});