diff -urN ../exim-4.91.orig/src/auths/plaintext.c ./src/auths/plaintext.c
--- ../exim-4.91.orig/src/auths/plaintext.c	2018-04-15 02:18:10.000000000 +0300
+++ ./src/auths/plaintext.c	2018-05-01 19:46:49.749989000 +0300
@@ -221,6 +221,7 @@
 
   for (i = 0; i < len; i++)
     if (ss[i] == '^')
+      {
       if (ss[i+1] != '^')
 	ss[i] = 0;
       else
@@ -229,6 +230,7 @@
         len--;
         memmove(ss + i, ss + i + 1, len - i);
         }
+      }
 
   /* The first string is attached to the AUTH command; others are sent
   unembellished. */