diff --git a/internal/server/handler.go b/internal/server/handler.go
index 0bb325a..42dc730 100644
--- a/internal/server/handler.go
+++ b/internal/server/handler.go
@@ -337,8 +337,8 @@ func (h *Handler) handlePost(s *Session, command string, arguments []string, id
 		if !parentMessage.Thread.Valid {
 			var parentHeader mail.Header
 			err = json.Unmarshal([]byte(parentMessage.HeaderRaw), &parentHeader)
-			parentMessageID := parentHeader["Message-ID"]
-			a.Thread = sql.NullString{String: parentMessageID[0], Valid: true}
+			parentMessageID := parentHeader.Get("Message-ID")
+			a.Thread = sql.NullString{String: parentMessageID, Valid: true}
 		} else {
 			a.Thread = parentMessage.Thread
 		}
diff --git a/internal/server/nntp_server.go b/internal/server/nntp_server.go
index d397212..1959d92 100644
--- a/internal/server/nntp_server.go
+++ b/internal/server/nntp_server.go
@@ -18,6 +18,7 @@ var (
 	Capabilities = protocol.Capabilities{
 		{Type: protocol.VersionCapability, Params: "2"},
 		{Type: protocol.ImplementationCapability, Params: fmt.Sprintf("%s %s", common.ServerName, common.ServerVersion)},
+		{Type: protocol.OverCapability, Params: "MSGID"},
 		{Type: protocol.ModeReaderCapability},
 	}
 )