diff --git a/linkcheck/checker/mailtourl.py b/linkcheck/checker/mailtourl.py
index 9d36f32d..e3450cce 100644
--- a/linkcheck/checker/mailtourl.py
+++ b/linkcheck/checker/mailtourl.py
@@ -159,7 +159,7 @@ class MailtoUrl (urlbase.UrlBase):
             {"addr": mail}, valid=False, overwrite=False)
             return
         # note: be sure to use rsplit since "@" can occur in local part
-        local, domain = mail.rsplit("@", 1)
+        local, domain = urlutil.decode_for_unquote(mail).rsplit("@", 1)
         if not local:
             self.set_result(_("Missing local part of mail address `%(addr)s'.") % \
             {"addr": mail}, valid=False, overwrite=False)
@@ -248,7 +248,7 @@ class MailtoUrl (urlbase.UrlBase):
         from dns.exception import DNSException
         log.debug(LOG_CHECK, "checking mail address %r", mail)
         mail = strformat.ascii_safe(mail)
-        username, domain = mail.rsplit('@', 1)
+        username, domain = urlutil.decode_for_unquote(mail).rsplit('@', 1)
         log.debug(LOG_CHECK, "looking up MX mailhost %r", domain)
         try:
             answers = resolver.query(domain, 'MX')
diff --git a/linkcheck/url.py b/linkcheck/url.py
index 2322cd76..ff40646c 100644
--- a/linkcheck/url.py
+++ b/linkcheck/url.py
@@ -256,8 +256,9 @@ def url_fix_common_typos (url):
 
 def url_fix_mailto_urlsplit (urlparts):
     """Split query part of mailto url if found."""
-    if "?" in urlparts[2]:
-        urlparts[2], urlparts[3] = urlparts[2].split('?', 1)
+    sep = b"?" if isinstance(urlparts[2], bytes) else u"?"
+    if sep in urlparts[2]:
+        urlparts[2], urlparts[3] = urlparts[2].split(sep, 1)
 
 # wayback urls include in the path http[s]://. By default the
 # tidying mechanism in linkchecker encodes the : and deletes the second slash