I've combined my file extension block list for email gateways with @HackerHurricane's from his Slideshare
here, @cyb3rops list from his ransomware prevention document
here, and Microsoft's list from
here. Let me know if you have more to add.
.386, .ace, .acm, .acv, .ade, .adp, .adt, .ani, .app, .arc, .arj, .asd, .asp, .asx, .avb, .ax, .bas, .bat, .bin, .boo, .btm, .cab, .cbt, .cdr, .cer, .chm, .cla, .cmd, .cnt, .cnv, .com, .cpl, .crt, .csc, .csh, .css, .der, .dll, .drv, .dvb, .email, .exe, .fon, .fxp, .gadget, .gms, .grp, .gvb, .hlp, .hpj, .ht, .HTA, .htlp, .htt, .inf, .ini, .ins, .iso, .isp, .its, .jar, .jnlp, .job, .js, .jse, .ksh, .lib, .lnk, .mad, .maf, .mag, .mam, .maq, .mar, .mas, .mat, .mau, .mav, .maw, .mcf, .mch, .mda, .mdb, .mde, .mdt, .mdw, .mdz, .mht, .mhtm, .mhtml, .mpd, .mpt, .msc, .msh, .msh1, .msh1xml, .msh2, .msh2xml, .mshxml, .MSI, .mso, .msp, .mst, .nws, .obd, .obj, .obt, .obz, .ocx, .ops, .osd, .ovl, .ovr, .pcd, .pci, .perl, .pgm, .pif, .pl, .plg, .pot, .prf, .prg, .ps1, .ps1xml, .ps2, .ps2xml, .psc1, .psc2, .pst, .pub, .pwz, .qpw, .reg, .sbf, .scf, .scr, .sct, .sfx, .sh, .shb, .shs, .shtml, .shw, .smm, .svg, .sys, .td0, .tlb, .tmp, .torrent, .tsk, .tsp, .tt6, .url, .vb, .vbe, .vbp, .vbs, .vbscript, .vbx, .vom, .vsd, .vsmacro, .vsmacros, .vss, .vst, .vsw, .vwp, .vxd, .vxe, .wbk, .wbt, .wiz, .wk, .wml, .wms, .wpc, .wpd, .ws, .wsc, .wsf, .wsh, .xbap, .xll, .xnk