diff --git a/include/protocol.h b/include/protocol.h
index 911c78d68..73373f881 100644
--- a/include/protocol.h
+++ b/include/protocol.h
@@ -92,9 +92,6 @@ public:
 	/* See ns_cert */
 	bool CanCertFP = false;
 
-	/* Can we send arbitrary message tags? */
-	bool CanSendTags = false;
-
 	/* Can users log out before being fully connected? */
 	bool CanSVSLogout = false;
 
@@ -288,6 +285,7 @@ public:
 	virtual bool IsIdentValid(const Anope::string &);
 	virtual bool IsHostValid(const Anope::string &);
 	virtual bool IsExtbanValid(const Anope::string &) { return false; }
+	virtual bool IsTagValid(const Anope::string &, const Anope::string &) { return false; }
 
 	/** Retrieve the maximum number of list modes settable on this channel
 	 * Defaults to Config->ListSize
diff --git a/modules/protocol/inspircd.cpp b/modules/protocol/inspircd.cpp
index 7cb86598a..17f6fb14a 100644
--- a/modules/protocol/inspircd.cpp
+++ b/modules/protocol/inspircd.cpp
@@ -117,7 +117,6 @@ public:
 		CanSVSHold = true;
 		CanSVSLogout = true;
 		CanCertFP = true;
-		CanSendTags = true;
 		RequiresID = true;
 		MaxModes = 20;
 		MaxLine = 4096;
@@ -583,6 +582,12 @@ public:
 
 		return true;
 	}
+
+	bool IsTagValid(const Anope::string &name, const Anope::string &tvalue)
+	{
+		// InspIRCd accepts arbitrary message tags.
+		return true;
+	}
 };
 
 class InspIRCdAutoOpMode final
diff --git a/src/process.cpp b/src/process.cpp
index a81340250..4ba0e23f0 100644
--- a/src/process.cpp
+++ b/src/process.cpp
@@ -126,17 +126,21 @@ bool IRCDProto::Parse(const Anope::string &buffer, Anope::map<Anope::string> &ta
 bool IRCDProto::Format(Anope::string &message, const Anope::map<Anope::string> &tags, const MessageSource &source, const Anope::string &command, const std::vector<Anope::string> &params)
 {
 	std::stringstream buffer;
-	if (CanSendTags && !tags.empty())
+	if (!tags.empty())
 	{
 		char separator = '@';
 		for (const auto &[tname, tvalue] : tags)
 		{
-			buffer << separator << tname;
-			if (!tvalue.empty())
-				buffer << '=' << tvalue;
-			separator = ';';
+			if (IRCD->IsTagValid(tname, tvalue))
+			{
+				buffer << separator << tname;
+				if (!tvalue.empty())
+					buffer << '=' << tvalue;
+				separator = ';';
+			}
 		}
-		buffer << ' ';
+		if (separator != '@')
+			buffer << ' ';
 	}
 
 	if (source.GetServer())