Up to 3 attachments can be added to a post. Maximum file size is 5 MB. The following file extensions are currently allowed:
3ds, bm, bmp,cfz,csv, dcl, doc, dst, dwf, dwfx, dwg, dxf, env,f3d, gif, gz, gzip, iam, idw, ipn, ipt, jfif, jpe, jpeg, jpg, log, lsp,nwc,nwd,nwf, pdf,pat, png, psd, rfa, rvt, svf,sdf, text, tif, tiff, txt, vcf,vtf,vtfx, xls, xml, zip,pkt,sdf,sdf2,sdf3,esri,shp,shx,dbf,prj
zip can always be used both to reduce file size and include other file types.
In addition, images can be embedded in a post using the Insert/Edt image option in the post editor toolbar