See if you want to do something with incoming data , then you need mapping ..otherwise no.
coming to your requirement-- if you have file (.txt) in AL11 folder in ecc, you can use file adapter at sender side and receiver side mail adapter , and in mail adapter you have check the mark for attachments.
if your requirement is something related to pick the data from table and convertion, you should go for proxy, then proxy will generate xml file,
that xml you have to convert in to xml in mail adapter and and attach