diff --git a/meta/lib/patchtest/mbox.py b/meta/lib/patchtest/mbox.py
index 2342fbda65..990ae02109 100644
--- a/meta/lib/patchtest/mbox.py
+++ b/meta/lib/patchtest/mbox.py
@@ -11,6 +11,7 @@
 #
 
 import email
+import patchtest_patterns
 import re
 
 # From: https://stackoverflow.com/questions/59681461/read-a-big-mbox-file-with-python
@@ -32,7 +33,7 @@ class MboxReader:
         lines = []
         while True:
             line = self.handle.readline()
-            if line == b'' or line.startswith(b'From '):
+            if line == b'' or patchtest_patterns.mbox_from.match(line):
                 yield email.message_from_bytes(b''.join(lines))
                 if line == b'':
                     break
diff --git a/meta/lib/patchtest/patchtest_patterns.py b/meta/lib/patchtest/patchtest_patterns.py
index b3478d2f0f..e12e85c65b 100644
--- a/meta/lib/patchtest/patchtest_patterns.py
+++ b/meta/lib/patchtest/patchtest_patterns.py
@@ -61,6 +61,10 @@ mbox_cover_letter_regex = pyparsing.Regex(r'\[\S+\s+0+/\d+\]')
 mbox_shortlog_maxlength = 90
 # based on https://stackoverflow.com/questions/30281026/regex-parsing-github-usernames-javascript
 mbox_github_username = pyparsing.Regex(r'\B(?<!\${)@([a-z0-9](?:-(?=[a-z0-9])|[a-z0-9]){0,38}(?<=[a-z0-9]))')
+# Standard mbox From_ separator line: "From <addr> Www Mmm [D]D HH:MM:SS YYYY"
+mbox_from = re.compile(
+    rb'^From \S+ \w{3} \w{3} [ \d]\d \d{2}:\d{2}:\d{2} \d{4}'
+)
 
 # patch