diff -urN ../exim-4.89.orig/src/deliver.c ./src/deliver.c
--- ../exim-4.89.orig/src/deliver.c	2017-03-04 23:21:35.000000000 +0200
+++ ./src/deliver.c	2017-06-24 19:06:58.354708000 +0300
@@ -8345,7 +8345,7 @@
 
 #ifdef SUPPORT_TLS
 if (!regex_STARTTLS) regex_STARTTLS =
-  regex_must_compile(US"\\n250[\\s\\-]STARTTLS(\\s|\\n|$)", FALSE, TRUE);
+  regex_must_compile(US"(^|\\n)250[\\s\\-]STARTTLS(\\s|\\n|$)", FALSE, TRUE);
 #endif
 
 if (!regex_CHUNKING) regex_CHUNKING =