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It is possible that the person absent did not introduce a replacement. In this case, the same OoO Business error
will be returned but without a substitute.
SendMessageRequest must then be called again and substitutes should be added next to the original
recipient. OoOProcessed under DestinationContext is set to true for the original recipient. For this recipient,
there will be no more OoO verification during the second request. If the message is to be sent encrypted, the
message must be encrypted again for the added substitute(s).
If the substitute himself is absent, a new OoO Business error will be returned, and so on.
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