Donald Jackson, federal prisoner # 25664-077, seeks a certificate of appealability (COA) to appeal the dismissal of his motion to modify his sentence pursuant to 18 U.S.C. § 3582(b)(2), in which he challenged his sentence for one count of assault with intent to steal money and property of the United States and one count of using or carrying a firearm in the commission of a crime of violence. The district court construed the motion as an unauthorized successive 28 U.S.C. § 2255 motion and dismissed it.
A COA may issue only if Jackson “has made a substantial showing of the denial of a constitutional right.” 28 U.S.C. § 2253(c)(2). Jackson, however, does not address the district court’s holding that his motion was an unauthorized successive § 2255 motion. He has therefore abandoned the only issue cognizable on appeal, see Hughes v. Johnson, 191 F.3d 607, 613 (5th Cir.1999), and this court need not address it.. See Brinkmann v. Dallas County Deputy Sheriff Abner, 813 F.2d 744, 748 (5th Cir.1987).
Jackson’s pleading in this court is without arguable merit and is frivolous. See Howard v. King, 707 F.2d 215, 219-20 (5th Cir.1983). Jackson has previously been sanctioned by this court for filing frivolous motions and has been warned about filing additional frivolous pleadings. See, e.g., In re Jackson, No. 04-10281 (5th Cir. Apr. 29, 2004) (unpublished). Because Jackson continues to file frivolous motions, IT IS ORDERED that he now pay sanctions in the amount of $300, payable to the Clerk *382of this Court. The Clerk of this Court and the clerks of all federal district courts within this circuit are directed to refuse to file any pro se civil complaint or appeal by Jackson unless Jackson submits proof of satisfaction of this sanction. If Jackson attempts to file any further notices of appeal or original proceedings in this court without such proof the clerk will docket them for administrative purposes only. Any other submissions which do not show proof that the sanction has been paid will neither be addressed nor acknowledged.
COA DENIED; SANCTION IMPOSED.