add "warn" log level

now that we are using slog, which has them.
and we already could use them for a deprecation warning.

mlog/log.go

@@ -71,6 +71,7 @@ var (
 	LevelTrace     = slog.LevelDebug - 4
 	LevelDebug     = slog.LevelDebug
 	LevelInfo      = slog.LevelInfo
+	LevelWarn      = slog.LevelWarn
 	LevelError     = slog.LevelError
 	LevelFatal     = slog.LevelError + 4 // Printed regardless of configured log level.
 	LevelPrint     = slog.LevelError + 8 // Printed regardless of configured log level.
@@ -83,6 +84,7 @@ var LevelStrings = map[slog.Level]string{
 	LevelTrace:     "trace",
 	LevelDebug:     "debug",
 	LevelInfo:      "info",
+	LevelWarn:      "warn",
 	LevelError:     "error",
 	LevelFatal:     "fatal",
 	LevelPrint:     "print",
@@ -95,6 +97,7 @@ var Levels = map[string]slog.Level{
 	"trace":     LevelTrace,
 	"debug":     LevelDebug,
 	"info":      LevelInfo,
+	"warn":      LevelWarn,
 	"error":     LevelError,
 	"fatal":     LevelFatal,
 	"print":     LevelPrint,
@@ -207,6 +210,17 @@ func (l Log) Infox(msg string, err error, attrs ...slog.Attr) {
 	l.Logger.LogAttrs(noctx, LevelInfo, msg, attrs...)
 }
 
+func (l Log) Warn(msg string, attrs ...slog.Attr) {
+	l.Logger.LogAttrs(noctx, LevelWarn, msg, attrs...)
+}
+
+func (l Log) Warnx(msg string, err error, attrs ...slog.Attr) {
+	if err != nil {
+		attrs = append([]slog.Attr{errAttr(err)}, attrs...)
+	}
+	l.Logger.LogAttrs(noctx, LevelWarn, msg, attrs...)
+}
+
 func (l Log) Error(msg string, attrs ...slog.Attr) {
 	l.Logger.LogAttrs(noctx, LevelError, msg, attrs...)
 }

mox-/config.go

@@ -1343,7 +1343,7 @@ func prepareDynamicConfig(ctx context.Context, log mlog.Log, dynamicPath string,
 			if !ok {
 				addErrorf("could not find localpart %q to replace with address in destinations", lp)
 			} else {
-				log.Error(`deprecation warning: support for account destination addresses specified as just localpart ("username") instead of full email address will be removed in the future; update domains.conf, for each Account, for each Destination, ensure each key is an email address by appending "@" and the default domain for the account`,
+				log.Warn(`deprecation warning: support for account destination addresses specified as just localpart ("username") instead of full email address will be removed in the future; update domains.conf, for each Account, for each Destination, ensure each key is an email address by appending "@" and the default domain for the account`,
 					slog.Any("localpart", lp),
 					slog.Any("address", addr),
 					slog.String("account", accName))

webadmin/admin.html

@@ -301,7 +301,7 @@ const config = async () => {
 const loglevels = async () => {
 	const loglevels = await api.LogLevels()
 
-	const levels = ['error', 'info', 'debug', 'trace', 'traceauth', 'tracedata']
+	const levels = ['error', 'info', 'warn', 'debug', 'trace', 'traceauth', 'tracedata']
 
 	let form, fieldset, pkg, level