Repositions the read point back to the start of the message.
After obtaining a message’s recipient list by repeated calls to mtaDequeueRecipientNext(), the read point into the underlying message file is positioned at the start of the actual message. Specifically, at the start of the message’s outermost header. Calling mtaDequeueLineNext() advances this read point, with each call moving it towards the end of the message. To reposition the read point back to the start of the message (that is, to the start of the message’s outermost header), call mtaDequeueRewind(). Use this call if a program needs to make a second pass through a message. For example, a program might scan a message’s content before actually processing it.