Change:
<del> { lib, stdenv, fetchurl, cabextract }: let fonts = [ { name = "andale";  sha256 = "0w7927hlwayqf3vvanf8f3qp2g1i404jzqvhp1z3mp0sjm1gw905"; } { name = "arial";   sha256 = "1xkqyivbyb3z9dcalzidf8m4npzfpls2g0kldyn8g73f2i6plac5"; } { name = "arialb";  sha256 = "1a60zqrg63kjnykh5hz7dbpzvx7lyivn3vbrp7jyv9d1nvzz09d4"; } { name = "comic";   sha256 = "0ki0rljjc1pxkbsxg515fwx15yc95bdyaksa3pjd89nyxzzg6vcw"; } { name = "courie";  sha256 = "111k3waxki9yyxpjwl2qrdkswvsd2dmvhbjmmrwyipam2s31sldv"; } { name = "georgi";  sha256 = "0083jcpd837j2c06kp1q8glfjn9k7z6vg3wi137savk0lv6psb1c"; } { name = "impact";  sha256 = "1yyc5z7zmm3s418hmrkmc8znc55afsrz5dgxblpn9n81fhxyyqb0"; } { name = "times";   sha256 = "1aq7z3l46vwgqljvq9zfgkii6aivy00z1529qbjkspggqrg5jmnv"; } { name = "trebuc";  sha256 = "1jfsgz80pvyqvpfpaiz5pd8zwlcn67rg2jgynjwf22sip2dhssas"; } { name = "webdin";  sha256 = "0nnp2znmnmx87ijq9zma0vl0hd46npx38p0cc6lgp00hpid5nnb4"; } { name = "verdan";  sha256 = "15mdbbfqbyp25a6ynik3rck3m3mg44plwrj79rwncc9nbqjn3jy1"; } { name = "wd97vwr"; sha256 = "1lmkh3zb6xv47k0z2mcwk3vk8jff9m845c9igxm14bbvs6k2c4gn"; } ]; eula = fetchurl { url = "https://corefonts.sourceforge.net/eula.htm"; sha256 = "1aqbcnl032g2hd7iy56cs022g47scb0jxxp3mm206x1yqc90vs1c"; }; in stdenv.mkDerivation { pname = "corefonts"; version = "1"; exes = map ({name, sha256}: fetchurl { url = "mirror://sourceforge/corefonts/${name}32.exe"; inherit sha256; }) fonts; nativeBuildInputs = [ cabextract ]; buildCommand = '' for i in $exes; do cabextract --lowercase $i done cabextract --lowercase viewer1.cab # rename to more standard names # handle broken macOS file-system mv andalemo.ttf  Andale_Mono.ttf mv ariblk.ttf    Arial_Black.ttf mv arial.ttf     Arial.ttf.tmp mv Arial.ttf.tmp Arial.ttf mv arialbd.ttf   Arial_Bold.ttf mv arialbi.ttf   Arial_Bold_Italic.ttf mv ariali.ttf    Arial_Italic.ttf mv comic.ttf     Comic_Sans_MS.ttf mv comicbd.ttf   Comic_Sans_MS_Bold.ttf mv cour.ttf      Courier_New.ttf mv courbd.ttf    Courier_New_Bold.ttf mv couri.ttf     Courier_New_Italic.ttf mv courbi.ttf    Courier_New_Bold_Italic.ttf mv georgia.ttf   Georgia.ttf.tmp mv Georgia.ttf.tmp   Georgia.ttf mv georgiab.ttf  Georgia_Bold.ttf mv georgiai.ttf  Georgia_Italic.ttf mv georgiaz.ttf  Georgia_Bold_Italic.ttf mv impact.ttf    Impact.ttf.tmp mv Impact.ttf.tmp    Impact.ttf mv tahoma.ttf    Tahoma.ttf.tmp mv Tahoma.ttf.tmp    Tahoma.ttf mv times.ttf     Times_New_Roman.ttf mv timesbd.ttf   Times_New_Roman_Bold.ttf mv timesbi.ttf   Times_New_Roman_Bold_Italic.ttf mv timesi.ttf    Times_New_Roman_Italic.ttf mv trebuc.ttf    Trebuchet_MS.ttf mv trebucbd.ttf  Trebuchet_MS_Bold.ttf mv trebucit.ttf  Trebuchet_MS_Italic.ttf mv trebucbi.ttf  Trebuchet_MS_Italic.ttf mv verdana.ttf   Verdana.ttf.tmp mv Verdana.ttf.tmp   Verdana.ttf mv verdanab.ttf  Verdana_Bold.ttf mv verdanai.ttf  Verdana_Italic.ttf mv verdanaz.ttf  Verdana_Bold_Italic.ttf mv webdings.ttf  Webdings.ttf.tmp mv Webdings.ttf.tmp  Webdings.ttf install -m444 -Dt $out/share/fonts/truetype *.ttf # Also put the EULA there to be on the safe side. cp ${eula} $out/share/fonts/truetype/eula.html # Set up no-op font configs to override any aliases set up by other packages. mkdir -p $out/etc/fonts/conf.d for name in Andale-Mono Arial-Black Arial Comic-Sans-MS  Courier-New Georgia Impact Times-New-Roman  Trebuchet Verdana Webdings ; do substitute ${./no-op.conf} $out/etc/fonts/conf.d/30-''${name,,}.conf  --subst-var-by fontname "''${name//-/ }" done ''; meta = with lib; { homepage = "https://corefonts.sourceforge.net/"; description = "Microsoft's TrueType core fonts for the Web"; platforms = platforms.all; license = licenses.unfreeRedistributable; # Set a non-zero priority to allow easy overriding of the # fontconfig configuration files. priority = 5; }; } </del>

Discussion:
Steps to reproduce the behavior: corefonts This package fails to build because all of the sourceforge mirrors all return "429 Too Many Requests" after making a certain number of requests. I'm not sure if the package needs to add a delay, find a different download host, or something else entirely. <!-- Please @ people who are in the list of the offending package or module. If in doubt, check for whoever last touched something. --Please run and paste the result. Add a :+1: [reaction] to [issues you find important]. [reaction]: [issues you find important]: