{"id":4165,"date":"2026-06-08T18:00:42","date_gmt":"2026-06-08T15:00:42","guid":{"rendered":"https:\/\/support.withsecure.com\/en\/?post_type=support_article&p=4165"},"modified":"2026-06-08T18:00:42","modified_gmt":"2026-06-08T15:00:42","slug":"message-is-getting-blocked-by-msg-maxsize-firewall-rule-despite-being-seemingly-smaller-than-the-limit","status":"publish","type":"support_article","link":"https:\/\/support.withsecure.com\/fr\/support-articles\/message-is-getting-blocked-by-msg-maxsize-firewall-rule-despite-being-seemingly-smaller-than-the-limit\/","title":{"rendered":"Message is getting blocked by MSG maxsize firewall rule despite being seemingly smaller than the limit"},"content":{"rendered":"

Issue:<\/h3>\n

Emails are blocked by the Messaging Security Gateway (MSG) or Protection Service for Email (PSE) maxsize <\/i>firewall rule despite being seemingly smaller than the limit.<\/p>\n

Resolution:<\/h3>\n

The maxsize<\/i> firewall rule may include\u00a0multiple criteria. Most likely one of the other criteria are being met by the message. Here is an example of the\u00a0maxsize <\/i>firewall rule criteria:<\/p>\n

Message size greater than 52428800 Bytes
OR \u00a0Attachment count greater than 256
OR \u00a0Total Uncompressed Attachment size greater than 52428800 Bytes
OR \u00a0File count in archive greater than 256
OR \u00a0File depth in archive greater than 20<\/p>\n

To check and modify the rule used in your appliance:<\/p>\n

    \n
  1. Log in to the MSG Web UI<\/li>\n
  2. Select the Email Protection<\/b>-tab<\/li>\n
  3. Navigate to Email Firewall -> Rules<\/b> using the left-side menu<\/li>\n
  4. Locate the rule called maxsize<\/i> from the list of rules<\/li>\n<\/ol>\n
      \n
    • The settings of the rule can be checked directly from the list<\/li>\n
    • To modify the rule, click on Edit Rule<\/b>, make the necessary changes and click Save changes<\/b><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

      Email attachment is getting dropped by the Messaging Security Gateway (MSG) or Protection Service for Email (PSE) maxsize firewall rule despite being seemingly smaller than the limit.<\/p>\n","protected":false},"template":"","support_article_product":[106],"class_list":["post-4165","support_article","type-support_article","status-publish","hentry"],"acf":{"source_foreign_id":"000005672","source_version":3,"source_system":"salesforce","source_date_updated":"2026-06-08 15:00:42","import_hash":"1781c3b6238226bba238206f94358bd2c553fb74","vanilla_article_id":31165,"vanilla_url":"https:\/\/community.withsecure.com\/en\/kb\/articles\/31165-message-is-getting-blocked-by-msg-maxsize-firewall-rule-despite-being-seemingly-smaller-than-the-limit","vanilla_kb_id":30,"vanilla_category_id":103,"machine_translated":false,"reactions_helpful_yes":0,"reactions_helpful_no":0},"_links":{"self":[{"href":"https:\/\/support.withsecure.com\/fr\/wp-json\/wp\/v2\/support_article\/4165","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/support.withsecure.com\/fr\/wp-json\/wp\/v2\/support_article"}],"about":[{"href":"https:\/\/support.withsecure.com\/fr\/wp-json\/wp\/v2\/types\/support_article"}],"wp:attachment":[{"href":"https:\/\/support.withsecure.com\/fr\/wp-json\/wp\/v2\/media?parent=4165"}],"wp:term":[{"taxonomy":"support_article_product","embeddable":true,"href":"https:\/\/support.withsecure.com\/fr\/wp-json\/wp\/v2\/support_article_product?post=4165"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}