diff --git a/go.mod b/go.mod
index c8fe25e..679e143 100644
--- a/go.mod
+++ b/go.mod
@@ -35,6 +35,7 @@ require (
 	github.com/tidwall/match v1.1.1 // indirect
 	github.com/tidwall/pretty v1.2.1 // indirect
 	github.com/tidwall/sjson v1.2.5 // indirect
+	github.com/yuin/goldmark v1.7.4 // indirect
 	go.mau.fi/util v0.7.0 // indirect
 	golang.org/x/crypto v0.26.0 // indirect
 	golang.org/x/exp v0.0.0-20240823005443-9b4947da3948 // indirect
diff --git a/go.sum b/go.sum
index b74992e..f4fb2bb 100644
--- a/go.sum
+++ b/go.sum
@@ -64,6 +64,8 @@ github.com/tidwall/pretty v1.2.1 h1:qjsOFOWWQl+N3RsoF5/ssm1pHmJJwhjlSbZ51I6wMl4=
 github.com/tidwall/pretty v1.2.1/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
 github.com/tidwall/sjson v1.2.5 h1:kLy8mja+1c9jlljvWTlSazM7cKDRfJuR/bOJhcY5NcY=
 github.com/tidwall/sjson v1.2.5/go.mod h1:Fvgq9kS/6ociJEDnK0Fk1cpYF4FIW6ZF7LAe+6jwd28=
+github.com/yuin/goldmark v1.7.4 h1:BDXOHExt+A7gwPCJgPIIq7ENvceR7we7rOS9TNoLZeg=
+github.com/yuin/goldmark v1.7.4/go.mod h1:uzxRWxtg69N339t3louHJ7+O03ezfj6PlliRlaOzY1E=
 go.mau.fi/util v0.7.0 h1:l31z+ivrSQw+cv/9eFebEqtQW2zhxivGypn+JT0h/ws=
 go.mau.fi/util v0.7.0/go.mod h1:bWYreIoTULL/UiRbZdfddPh7uWDFW5yX4YCv5FB0eE0=
 golang.org/x/crypto v0.26.0 h1:RrRspgV4mU+YwB4FYnuBoKsUapNIL5cohGAmSH3azsw=
diff --git a/internal/matrix/client.go b/internal/matrix/client.go
index 8b0c5a6..74e370f 100644
--- a/internal/matrix/client.go
+++ b/internal/matrix/client.go
@@ -11,16 +11,24 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/sebhoss/matrix-alertmanager-receiver/internal/config"
-	"html"
 	"log/slog"
 	"maunium.net/go/mautrix"
 	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/format"
 	"maunium.net/go/mautrix/id"
 	"os"
-	"regexp"
+	"slices"
 )
 
 var (
+	joinRoomSuccessTotal = promauto.NewCounterVec(prometheus.CounterOpts{
+		Name: "matrix_alertmanager_receiver_join_room_success_total",
+		Help: "The total number of successful join room operations",
+	}, []string{"room"})
+	joinRoomFailureTotal = promauto.NewCounterVec(prometheus.CounterOpts{
+		Name: "matrix_alertmanager_receiver_join_room_failure_total",
+		Help: "The total number of failed join room operations",
+	}, []string{"room"})
 	sendSuccessTotal = promauto.NewCounter(prometheus.CounterOpts{
 		Name: "matrix_alertmanager_receiver_send_success_total",
 		Help: "The total number of successful send operations",
@@ -33,38 +41,22 @@ var (
 
 type SendingFunc func(htmlText string, roomID string)
 
-// An HTMLMessage is the contents of a Matrix HTML formated message event.
-type HTMLMessage struct {
-	Body          string `json:"body"`
-	MsgType       string `json:"msgtype"`
-	Format        string `json:"format"`
-	FormattedBody string `json:"formatted_body"`
-}
-
-var htmlRegex = regexp.MustCompile("<[^<]+?>")
-
-// GetHTMLMessage returns an HTMLMessage with the body set to a stripped version of the provided HTML, in addition
-// to the provided HTML.
-func GetHTMLMessage(msgtype, htmlText string) HTMLMessage {
-	return HTMLMessage{
-		Body:          html.UnescapeString(htmlRegex.ReplaceAllLiteralString(htmlText, "")),
-		MsgType:       msgtype,
-		Format:        "org.matrix.custom.html",
-		FormattedBody: htmlText,
-	}
-}
+var joinedRoomIDs []string
 
 func CreatingSendingFunc(ctx context.Context, configuration config.Matrix) SendingFunc {
 	matrixClient := createMatrixClient(ctx, configuration)
+	fetchJoinedRooms(ctx, matrixClient)
 	return func(htmlText string, room string) {
 		mappedRoom := room
 		if mapped, ok := configuration.RoomMapping[room]; ok {
 			mappedRoom = mapped
 		}
-		if _, err := matrixClient.JoinRoom(ctx, mappedRoom, "", nil); err != nil {
+		if err := joinRoom(ctx, matrixClient, mappedRoom); err != nil {
+			joinRoomFailureTotal.WithLabelValues(mappedRoom).Inc()
 			slog.ErrorContext(ctx, fmt.Sprintf("Could not join room %s", room), slog.Any("error", err))
 		} else {
-			if respSendEvent, err := matrixClient.SendMessageEvent(ctx, id.RoomID(room), event.NewEventType("m.room.message"), GetHTMLMessage("m.text", htmlText)); err != nil {
+			joinRoomSuccessTotal.WithLabelValues(mappedRoom).Inc()
+			if respSendEvent, err := matrixClient.SendMessageEvent(ctx, id.RoomID(mappedRoom), event.NewEventType("m.room.message"), format.HTMLToContent(htmlText)); err != nil {
 				sendFailureTotal.Inc()
 				slog.ErrorContext(ctx, "Could not send message to Matrix homeserver", slog.Any("error", err))
 			} else {
@@ -82,8 +74,30 @@ func createMatrixClient(ctx context.Context, configuration config.Matrix) *mautr
 	if matrixClient, err = mautrix.NewClient(configuration.HomeServerURL, id.UserID(configuration.UserID), configuration.AccessToken); err != nil {
 		slog.ErrorContext(ctx, "Failed to create matrix client", slog.Any("error", err))
 		os.Exit(1)
-	} else {
-		slog.DebugContext(ctx, "Created Matrix client")
 	}
+	slog.DebugContext(ctx, "Created Matrix client")
 	return matrixClient
 }
+
+func fetchJoinedRooms(ctx context.Context, client *mautrix.Client) {
+	joinedRooms, err := client.JoinedRooms(ctx)
+	if err != nil {
+		slog.ErrorContext(ctx, "Could not fetch Matrix rooms", slog.Any("error", err))
+		os.Exit(1)
+	}
+	for _, roomID := range joinedRooms.JoinedRooms {
+		joinedRoomIDs = append(joinedRoomIDs, roomID.String())
+	}
+}
+
+func joinRoom(ctx context.Context, client *mautrix.Client, roomToJoin string) error {
+	if !slices.Contains(joinedRoomIDs, roomToJoin) {
+		slog.DebugContext(ctx, "Joining room", slog.String("room", roomToJoin))
+		_, err := client.JoinRoom(ctx, roomToJoin, "", nil)
+		if err != nil {
+			return err
+		}
+		joinedRoomIDs = append(joinedRoomIDs, roomToJoin)
+	}
+	return nil
+}