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This happens because Microsoft Exchange Server is reformatting messages sent through it.
The Exchange server insists that message text must always be first and attachments must always be last. As soon as the Exchange software sees one attachment in a message, it stops looking for text, and treats anything else in that message as an attachment. Any remaining text sections are converted into attachment sections, and given fake file names (like "ATT00001.htm").
There is no way to make the Exchange server stop turning text sections into attachment sections.
This happens because Microsoft Exchange Server is reformatting messages sent through it.
The Exchange server insists that message text must always be first and attachments must always be last. As soon as the Exchange software sees one attachment in a message, it stops looking for text, and treats anything else in that message as an attachment. Any remaining text sections are converted into attachment sections, and given fake file names (like "ATT00001.htm").
There is no way to make the Exchange server stop turning text sections into attachment sections.