diff --git a/nixos/modules/mail.nix b/nixos/modules/mail.nix
index d05ab81..85ce577 100644
--- a/nixos/modules/mail.nix
+++ b/nixos/modules/mail.nix
@@ -252,7 +252,8 @@ in {
               echo "process ${domain}"
               # This line gets the available mailboxes from stalwart's Rest API, searches for their addresses and collects them to a file for submission.
               # The regex searches for alphanumerics combined with some special characters as local paths and the right domain.
-              ${pkgs.curl}/bin/curl -s --header "authorization: Basic $(<${cfg.stalwartAdmin})" http://localhost/api/principal | ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" | tee /tmp/addresses
+              # Exclude @domain.tld which is not a valid mail address but used for catch-all accounts.
+              ${pkgs.curl}/bin/curl -s --header "authorization: Basic $(<${cfg.stalwartAdmin})" http://localhost/api/principal | ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" | grep -v "@${domain}" | tee /tmp/addresses
               # This line searches for available redirects and adds them to the submission file.
               ${pkgs.gnugrep}/bin/grep -o -e "[A-Za-z0-9.!#\$%&'*+-/=?^_{|}~]*@${domain}" /tmp/virt_aliases >> /tmp/addresses # This doesn't catch all RFC conform local parts. Improve if you need.
               # Post local-parts to HRZ, see https://www-cgi.hrz.tu-darmstadt.de/mail/index.php?bereich=whitelist_upload