diff --git a/roles/mail_forwarder/templates/main.cf.j2 b/roles/mail_forwarder/templates/main.cf.j2
index 35f1f0a704341ed634f26121c5bb78c1aa626a96..6322eb1b18acb175035d1228c3d24d6865fc3b8f 100644
--- a/roles/mail_forwarder/templates/main.cf.j2
+++ b/roles/mail_forwarder/templates/main.cf.j2
@@ -47,3 +47,6 @@ recipient_delimiter = +
 # Fall-back to using native lookups (/etc/hosts etc) if DNS lookup fails. Useful
 # for local overrides of mail servers.
 smtp_host_lookup = dns, native
+
+# Explicitly set maximum allowed mail size that should be accepted.
+message_size_limit = {{ mail_message_size_limit }}