diff --git a/getmailcore/baseclasses.py b/getmailcore/baseclasses.py
index 7143886..e94ba0d 100755
--- a/getmailcore/baseclasses.py
+++ b/getmailcore/baseclasses.py
@@ -261,7 +261,7 @@ class ConfFile(ConfString):
         if val is None:
             return None
         val = expand_user_vars(val)
-        if not os.path.isfile(val):
+        if not os.path.isfile(val) and not self.name == 'path' and not self.name == 'password_command':
             raise getmailConfigurationError(
                 '%s: specified file "%s" does not exist' % (self.name, val)
             )
@@ -473,7 +473,7 @@ class ForkingBase(object):
                          stdout, stderr, args, nolog=False):
         self._pipemail(msg, delivered_to, received, unixfrom, stdout, stderr)
         nolog or self.log.debug('about to execl() with args %s\n' % str(args))
-        os.execl(*args)
+        os.execlp(*args)
 
     def forkchild(self, childfun, with_out=True):
         self.child = child = Namespace()
diff --git a/getmailcore/destinations.py b/getmailcore/destinations.py
index 2d25558..d7adeba 100755
--- a/getmailcore/destinations.py
+++ b/getmailcore/destinations.py
@@ -607,9 +607,9 @@ class MDA_external(DeliverySkeleton, ForkingBase):
     def initialize(self):
         self.log.trace()
         self.conf['command'] = os.path.basename(self.conf['path'])
-        if not os.access(self.conf['path'], os.X_OK):
-            raise getmailConfigurationError('%s not executable'
-                                            % self.conf['path'])
+        # if not os.access(self.conf['path'], os.X_OK):
+        #     raise getmailConfigurationError('%s not executable'
+        #                                     % self.conf['path'])
         if type(self.conf['arguments']) != tuple:
             raise getmailConfigurationError(
                 'incorrect arguments format; see documentation (%s)'
diff --git a/getmailcore/filters.py b/getmailcore/filters.py
index e118e8e..014970a 100755
--- a/getmailcore/filters.py
+++ b/getmailcore/filters.py
@@ -193,10 +193,10 @@ class Filter_external(FilterSkeleton, ForkingBase):
     def initialize(self):
         self.log.trace()
         self.conf['command'] = os.path.basename(self.conf['path'])
-        if not os.access(self.conf['path'], os.X_OK):
-            raise getmailConfigurationError(
-                '%s not executable' % self.conf['path']
-            )
+        # if not os.access(self.conf['path'], os.X_OK):
+        #    raise getmailConfigurationError(
+        #        '%s not executable' % self.conf['path']
+        #    )
         if type(self.conf['arguments']) != tuple:
             raise getmailConfigurationError(
                 'incorrect arguments format; see documentation (%s)'
@@ -332,10 +332,10 @@ class Filter_TMDA(FilterSkeleton, ForkingBase):
     def initialize(self):
         self.log.trace()
         self.conf['command'] = os.path.basename(self.conf['path'])
-        if not os.access(self.conf['path'], os.X_OK):
-            raise getmailConfigurationError(
-                '%s not executable' % self.conf['path']
-            )
+        # if not os.access(self.conf['path'], os.X_OK):
+        #     raise getmailConfigurationError(
+        #         '%s not executable' % self.conf['path']
+        #     )
         self.exitcodes_keep = (0, )
         self.exitcodes_drop = (99, )