Handle TAB, not just SP, in MAIL args.

Analysis, diagnosis and variant patch by Todd Lyons.

2 files changed, 6 insertions, 1 deletions

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index f24e1a8f9..ee63f414e 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -41,6 +41,10 @@ PP/10 Added dbmjz lookup type.
 
 PP/11 Let heimdal_gssapi authenticator take a SASL message without an authzid.
 
+PP/12 MAIL args handles TAB as well as SP, for better interop with
+      non-compliant senders.
+      Analysis and variant patch by Todd Lyons.
+
 
 Exim version 4.77
 -----------------
diff --git a/src/src/smtp_in.c b/src/src/smtp_in.c
index e79f0a202..476bbf0c2 100644
--- a/src/src/smtp_in.c
+++ b/src/src/smtp_in.c
@@ -983,7 +983,8 @@ if (*v != '=') return FALSE;
 n = v;
 while(isalpha(n[-1])) n--;
 
-if (n[-1] != ' ') return FALSE;
+/* RFC says SP, but TAB seen in wild and other major MTAs accept it */
+if (!isspace(n[-1])) return FALSE;
 
 n[-1] = 0;
 *name = n;