diff --git a/DMARC-how-to.md b/DMARC-how-to.md
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@@ -4,7 +4,12 @@
 This how-to is created by the Dutch Internet Standards Platform (the organization behind [internet.nl](https://internet.nl)) and is meant to provide practical information and guidance on implementing DMARC.
 
 # What is DMARC?
-DMARC is short for **D**omain based **M**essage **A**uthentication, **R**eporting and **C**onformance and is described in...
-
+DMARC is short for **D**omain based **M**essage **A**uthentication, **R**eporting and **C**onformance and is described in [RFC 7489](https://tools.ietf.org/html/rfc7489). With DMARC the owner of a domain can, by means of a DNS record, publish a  policy that states how to handle e-mail which is not properly authenticated using SPF and/or DKIM. At the same time it provides the means for receiving reports which allows a domain's administrator to detect whether their domainname is used for phishing or spam.
+ 
 # Why use DMARC?
 to-do.
+
+# Tips, tricks and notices for implementation
+* Interoperabily issues: https://tools.ietf.org/html/rfc7960
+* DMARC does not require both DKIM or SPF. 
+*