IFetchRequestChangedSince Property

ulong? ChangedSince { get; set; }

Property Value

Gets or sets the mod-sequence value that indicates the last known state of the messages being requested.

If this property is set, the results returned by Fetch or FetchAsync will only include the message summaries which have a higher mod-sequence value than the one specified.

If the mail store supports quick resynchronization and the application has enabled this feature via EnableQuickResync(CancellationToken), then the Fetch or FetchAsync method will emit MessagesVanished events for messages that were expunged from the folder after the change specified by the mod-sequence value.

It should be noted that if another client has modified any message in the folder, the mail service may choose to return information that was not explicitly requested. It is therefore important to be prepared to handle both additional fields on a IMessageSummary for messages that were requested as well as summaries for messages that were not requested at all.

Reference