diff -urN ../exim-4.94.orig/src/lookups/readsock.c ./src/lookups/readsock.c
--- ../exim-4.94.orig/src/lookups/readsock.c	2020-05-30 23:35:38.000000000 +0300
+++ ./src/lookups/readsock.c	2021-05-10 21:48:04.737743000 +0300
@@ -249,7 +249,8 @@
 writable mode or the underlying socket goes non-writable. */
 
 if (!cctx->tls_ctx)
-  fp = fdopen(cctx->sock, lf.do_shutdown ? "rb" : "wb");
+//  fp = fdopen(cctx->sock, lf.do_shutdown ? "rb" : "wb");
+  fp = fdopen(cctx->sock, "rb");
 
 sigalrm_seen = FALSE;
 ALARM(timeout);