initial, rought, not-user-friendly support for multi-domain setup

config/config.go

@@ -15,7 +15,7 @@ func New() *Config {
 		Login:        env.String("login", defaultConfig.Login),
 		Password:     env.String("password", defaultConfig.Password),
 		Prefix:       env.String("prefix", defaultConfig.Prefix),
-		Domain:       env.String("domain", defaultConfig.Domain),
+		Domains:      migrateDomains("domain", "domains"),
 		Port:         env.String("port", defaultConfig.Port),
 		NoEncryption: env.Bool("noencryption"),
 		DataSecret:   env.String("data.secret", defaultConfig.DataSecret),
@@ -40,3 +40,13 @@ func New() *Config {
 
 	return cfg
 }
+
+func migrateDomains(oldKey, newKey string) []string {
+	domains := []string{}
+	old := env.String(oldKey, "")
+	if old != "" {
+		domains = append(domains, old)
+	}
+
+	return append(domains, env.Slice(newKey)...)
+}

config/defaults.go

@@ -2,7 +2,7 @@ package config
 
 var defaultConfig = &Config{
 	LogLevel:  "INFO",
-	Domain:    "localhost",
+	Domains:   []string{"localhost"},
 	Port:      "25",
 	Prefix:    "!pm",
 	MaxSize:   1024,

config/types.go

@@ -8,8 +8,8 @@ type Config struct {
 	Login string
 	// Password for login/password auth only
 	Password string
-	// Domain for SMTP
-	Domain string
+	// Domains for SMTP
+	Domains []string
 	// Port for SMTP
 	Port string
 	// RoomID of the admin room