diff --git a/NEWS b/NEWS
index 65fb408ddaa..b3ac9d6b405 100644
--- a/NEWS
+++ b/NEWS
@@ -261,6 +261,8 @@ PHP                                                                        NEWS
   . Added array_first() and array_last(). (nielsdos)
   . Fixed bug GH-18823 (setlocale's 2nd and 3rd argument ignores strict_types).
     (nielsdos)
+  . Fixed exit code handling of sendmail cmd and added warnings.
+    (Jesse Hathaway)
 
 - Streams:
   . Fixed bug GH-16889 (stream_select() timeout useless for pipes on Windows).
diff --git a/UPGRADING b/UPGRADING
index 4c6e40cfdeb..1462be95a43 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -217,6 +217,12 @@ PHP 8.5 UPGRADE NOTES
     Sqlite3Stmt::EXPLAIN_MODE_EXPLAIN and
     Sqlite3Stmt::EXPLAIN_MODE_EXPLAIN_QUERY_PLAN.
 
+- Standard:
+  . mail() now returns the actual sendmail error and detects if the sendmail
+    process was terminated unexpectedly. In such cases, a warning is emitted
+    and the function returns false. Previously, these errors were silently
+    ignored. This change affects only the sendmail transport.
+
 - XSL:
   . The $namespace argument of XSLTProcessor::getParameter(),
     XSLTProcessor::setParameter() and XSLTProcessor::removeParameter()