--- title: "Why do I get an \"Anti-spam error\" message when sending?" description: The error code 3524 or Anti spam error. Perm means that your sending attempt has failed due to fraud suspicion or a prohibited OADC --- [Skip to content](https://support.smsmode.com/en/base-de-connaissance/anti-spam-error-sending#main-content) English Show submenu for translations [More support](https://support.smsmode.com/en/base-de-connaissance/kb-tickets/new?hsLang=en) [Customer portal](https://ticket.smsmode.com/tickets-view?hsLang=en) [![logo-smsmode-2019-long 1-2.png\]](https://support.smsmode.com/hs-fs/hubfs/logo-smsmode-2019-long%201-2.png?width=140&height=38&name=logo-smsmode-2019-long%201-2.png)](https://support.smsmode.com/en/base-de-connaissance?hsLang=en) - [API documentation](https://dev.smsmode.com/) - [My tickets](https://ticket.smsmode.com/tickets-view?offset=0) - [Log out](https://26532669.hs-sites-eu1.com/_hcms/mem/logout) Open main navigation Close main navigation - [API documentation](https://dev.smsmode.com/) - [My tickets](https://ticket.smsmode.com/tickets-view?offset=0) - [Log out](https://26532669.hs-sites-eu1.com/_hcms/mem/logout) - English Show submenu for translations - [More support](https://support.smsmode.com/en/base-de-connaissance/kb-tickets/new) - [Customer portal](https://ticket.smsmode.com/tickets-view) - [smsmode.com](https://www.smsmode.com/en/) [smsmode.com](https://www.smsmode.com/en/) Hello! How can we help you today? - There are no suggestions because the search field is empty. 1. [Portail support et base de connaissance - smsmode](https://support.smsmode.com/en/base-de-connaissance?hsLang=en) 2. [Basic Functionalities](https://support.smsmode.com/en/base-de-connaissance/basic-functionalities?hsLang=en) 3. [Campaign Management](https://support.smsmode.com/en/base-de-connaissance/basic-functionalities?hsLang=en#campaign-management) # Why do I get an "Anti-spam error" message when sending? ## The two reasons for the anti-spam error code. The error code "3524" or "Anti spam error. Perm" means that your sending attempt has failed due to fraud suspicion or a prohibited OADC (Sender ID) in the destination country. If your messages are legit an element of your message may have triggered the smsmode© spam filter. #### 2 types of content are blocked: - Some Sender IDs (OADC for Originator ADdress Code) - Some URLs in the message body ### Sender ID Rules: Due to the increase of smishing, the authorities (Operators, AF2M, A2C and aggregators) have implemented several actions to prevent SMS phishing. Among which **blocking certain personalized senders** (Sender ID). **4 types of sender blocking are applied :** #### OADC (Sender ID) strictly prohibited: A list of sensitive or overly generic sender IDs that can be used to mislead recipients (e.g. SFR, ANTAI, Ameli, reservation, delivery, etc.) is prohibited. #### OADC (Sender ID) prohibited unless authorized: Sender IDs representing existing brands, banks or institutions are also prohibited, and cannot be used without the official agreement of the brands/institutions in question (BNP, Netflix, Amazon, Chronopost, etc.). #### OADC (Sender ID) with special characters: The use of special characters to mislead the recipient is prohibited (e.g. ap\>le in an attempt to reproduce Apple, compte:gouv, etc.). Non-exhaustive list of prohibited special characters: \* |\< !? ; ' Some separator characters (- \_ &) are permitted. #### OADC (Sender ID) with abnormal numbers: Customized senders containing digits to imitate a telephone number or short code are also prohibited. If you think that your Sender ID prevent issuing your sending, contact us at [sales@smsmode.com](mailto:sales@smsmode.com) or by phone: +44 20 3514 2545 ### URL rules : In the vast majority of smishing attempts, a URL link is included in the SMS to redirect the recipient to a fraudulent website. smsmode© has therefore decided to block all URLs. 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