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You would do this the same way whether you have one or many attachments. You should be able to find sample code - a lot depends on where you plan to store these. https://support.microsoft.com/en-us/help/2517906/how-to-encode-and-to-decode-a-file-attachment-programmatically-by-usin has a code sample. qRules also can do this for you, if you don't want to write code - it saves attachments out to a SharePoint library.