diff --git a/doc/Tags-and-Mentions.md b/doc/Tags-and-Mentions.md
index 5501d0d580..eac2c97f84 100644
--- a/doc/Tags-and-Mentions.md
+++ b/doc/Tags-and-Mentions.md
@@ -21,11 +21,22 @@ You can tag a person on a different network or one that is **not in your social
 	
 * @mike@macgirvin.com - This is called a "remote mention" and can only be an email-style locator, not a web URL.
 
-Unless their system blocks unsolicited "mentions", the person tagged will likely receive a "Mention" post/activity or become a direct participant in the conversation in the case of public posts. Please note that Friendica blocks incoming "mentions" from people with no relationship to you. This is a spam prevention measure.
+Unless their system blocks unsolicited "mentions", the person tagged will likely receive a "Mention" post/activity or become a direct participant in the conversation in the case of public posts.
+Friendica blocks incoming “mentions” from people with no relationship to you.
+The exception is an ongiong conversation started from a contact of both you and the 3rd person or a conversation in a forum where you are a member of.
+This is a spam prevention measure.
 
-Remote mentions are delivered using the OStatus protocol. This protocol is used by Friendica and GNU Social and several other systems, but is not currently implemented in Diaspora. 
+Remote mentions are delivered using the OStatus protocol.
+This protocol is used by Friendica and GNU Social and several other systems, but is not currently implemented in Diaspora. 
+As the OStatus protocol allows this Friendica user can be @-mentioned by users from platforms using this protocol in conversations if the "Enable OStatus support" is activated on the Friendica node.
+These @-mentions wont be blocked, even if there is no relationship between the sender and the receiver of the message.
 
-Friendica makes no distinction between people and groups for the purpose of tagging. (Some other networks use !group to indicate a group.)
+Friendica makes no distinction between people and forums for the purpose of tagging.
+(Some other networks use !forum to indicate a forum.)
+
+If you sort your contacts into groups, you cannot @-mention these groups.
+But you can select the group in the access control when creating a new posting, to allow (or disallow) a certain group of people to see the posting.
+See [Groups and Privacy](help/Groups-and-Privacy) for more details about grouping your contacts.
 
 **Topical Tags**