Messages that are in the MXSave webmail could be there for up to 30 days upon which they are automatically purged. 

The messages in webmail are not indicative of whether messages have been delivered to the primary mail server. 

The spooling server operates separately with a different copy of the messages. To see whether anything is left in the spooler, simply click the magnifying glass icon next to your domain in the MXSave admin interface and that will look through the queues which will report how many messages are residing in queues.