Commented out the call to Net::SMTP's verify() method and replaced it with a generic regexp sanity check. It appears that VRFY is not correctly implemented on all servers. (I may be mistaken on this; it might just be a bug somewhere in the PLIF code that is messing something up, but I couldn't find it if so.)

webtools/PLIF/PLIF/Output/Generic/Email.pm

@@ -89,9 +89,12 @@ sub output {
 sub checkAddress {
     my $self = shift;
     my($app, $username) = @_;
-    $self->assert(defined($self->handle), 1, 'No SMTP handle, can\'t check address');
-    my $result = $self->handle->verify($username);
-    return $result;
+    return (defined($username) and $username =~ m/^[^@\s]+@[^@\s]+\.[^@.\s]+$/os);
+    # XXX this doesn't seem to be working:
+    # $self->assert(defined($self->handle), 1, 'No SMTP handle, can\'t check address');
+    # $self->assert(defined($username), 1, 'Internal error: no username passed to checkAddress');
+    # my $result = $self->handle->verify($username);
+    # return $result;
 }
 
 sub DESTROY {