SubscriptionOptionsRetainHandling Property

Retain handling option. This specifies whether retained messages are sent when the subscription is established. This does not affect the sending of retained messages at any point after the subscribe. If there are no retained messages matching the Topic Filter, all of these values act the same. The values are:

0 = Send retained messages at the time of the subscribe.

1 = Send retained messages at subscribe only if the subscription does not currently exist.

2 = Do not send retained messages at the time of the subscribe.

public int RetainHandling { get; set; }