Sender mail adapter - filter emails by attachment?

Dear experts,

I have a sender mail adapter that picks an XSL (EXCEL) attachment from an incoming email and converts it (with a custom adapter module) to XML.

But now how can I make the adapter only process emails with XLS - attachments? In that Inbox I also have emails with HTML-attachments for example. And now my adapter also wants to process those messages.

In my adapter module that makes XLS to XML I see an exception in RWB but the message still gets through to SXMB_MONI where it gets stuck with a red flag.

Can I somehow tell the adapter to only process emails with XLS attachments?

Or can I stop the processing in the adapter module that converts XLS to XML?

Thank you for any input or ideas on this!

Best regards,

Peter

PS: I am using this code to convert XLS to XML:

http://wiki.sdn.sap.com/wiki/display/ABAP/AdapterModuleToReadExcelFilewithMultipleRowsandMultiple+Columns