diff --git a/reference/mbstring/functions/mb-send-mail.xml b/reference/mbstring/functions/mb-send-mail.xml
index 9ae2e3f3ae..182063ce4b 100644
--- a/reference/mbstring/functions/mb-send-mail.xml
+++ b/reference/mbstring/functions/mb-send-mail.xml
@@ -55,14 +55,40 @@
- additional_headers
+ additional_headers (optional)
- additional_headers is inserted at
- the end of the header. This is typically used to add extra
- headers. Multiple extra headers are separated with a
- newline ("\n").
+ String to be inserted at the end of the email header.
+
+ This is typically used to add extra headers (From, Cc, and Bcc).
+ Multiple extra headers should be separated with a CRLF (\r\n).
+
+
+
+ When sending mail, the mail must contain
+ a From header. This can be set with the
+ additional_headers parameter, or a default
+ can be set in &php.ini;.
+
+
+ Failing to do this will result in an error
+ message similar to Warning: mail(): "sendmail_from" not
+ set in php.ini or custom "From:" header missing.
+ The From header sets also
+ Return-Path under Windows.
+
+
+
+
+ If messages are not received, try using a LF (\n) only.
+ Some Unix mail transfer agents (most notably
+ qmail) replace LF by CRLF
+ automatically (which leads to doubling CR if CRLF is used).
+ This should be a last resort, as it does not comply with
+ RFC 2822.
+
+