Whether aiding and abetting a mail offense constitutes a crime of violence for sentencing enhancement purposes and what standard of review applies to categorical approach determinations

I. Does aiding and abetting a mail offense pursuant to 18 U.S.C. § 2114(a) constitute a crime of violence for purposes of serving as a predicate offense under 18 U.S.C. § 924(c)? II. Does an appellate court apply de novo review or clear error review to a district court’s determination of the crime of conviction under the modified categorical approach?