Abort upon missing recipient key.

Do not proceed with encryption if no key can be found for a given
recipient.

src/fmail.c

@@ -409,11 +409,12 @@ get_recipient_keys(gpgme_ctx_t ctx, const char **recipients, size_t nr)
 {
     gpgme_key_t *keys, key;
     gpgme_error_t gerr;
-    int i, j;
+    int i, j, k;
 
     keys = NULL;
 
     for ( i = j = gerr = 0; i < nr && ! gerr ; i++ ) {
+        k = j;
         gerr = gpgme_op_keylist_start (ctx, recipients[i], 0);
         while ( ! gerr ) {
             gerr = gpgme_op_keylist_next (ctx, &key);
@@ -426,6 +427,9 @@ get_recipient_keys(gpgme_ctx_t ctx, const char **recipients, size_t nr)
         }
         if ( gpgme_err_code(gerr) == GPG_ERR_EOF )
             gerr = 0;
+
+        if ( k == j )
+            errx(EXIT_FAILURE, "no key found for recipient %s", recipients[i]);
     }
     if ( gerr != 0 && gpgme_err_code(gerr) != GPG_ERR_EOF)
         errx(EXIT_FAILURE, "cannot get recipient keys: %s", gpgme_strerror(gerr));