diff --git a/README.md b/README.md
index 08d789d..8628697 100644
--- a/README.md
+++ b/README.md
@@ -44,10 +44,12 @@ On local PC (192.168.1.54) create file `/etc/mailrelay.json` with contents:
     "smtp_starttls": false,
     "smtp_username": "username@fastmail.com",
     "smtp_password": "secretAppPassword",
+    "smtp_max_email_size": 10485760,
     "smtp_login_auth_type": false,
     "local_listen_ip": "0.0.0.0",
     "local_listen_port": 2525,
-    "allowed_hosts": ["*"]
+    "allowed_hosts": ["*"],
+    "timeout_secs": 30
 }
 ```
 
diff --git a/mailrelay.json b/mailrelay.json
index 778d70b..e33be85 100644
--- a/mailrelay.json
+++ b/mailrelay.json
@@ -4,9 +4,11 @@
 	"smtp_starttls": false,
 	"smtp_login_auth_type": false,
 	"smtp_username": "username@fastmail.com",
-	"smtp_password": "secret_app_password",
+    "smtp_password": "secret_app_password",
+    "smtp_max_email_size": 83886080,
 	"smtp_skip_cert_verify": false,
 	"local_listen_port": 2525,
 	"local_listen_ip": "0.0.0.0",
-	"allowed_hosts": ["*"]
+    "allowed_hosts": ["*"],
+    "timeout_secs": 30
 }
diff --git a/main.go b/main.go
index c1d8010..d2939a6 100644
--- a/main.go
+++ b/main.go
@@ -12,6 +12,14 @@ import (
 	log "github.com/flashmob/go-guerrilla/log"
 )
 
+const (
+	DefaultSTMPPort        = 465
+	DefaultMaxEmailSize    = (10 << 23) // 83 MB
+	DefaultLocalListenIP   = "0.0.0.0"
+	DefaultLocalListenPort = 2525
+	DefaultTimeoutSecs     = 300 // 5 minutes
+)
+
 // Logger is the global logger
 var Logger log.Logger
 
@@ -23,9 +31,11 @@ type mailRelayConfig struct {
 	SMTPUsername      string   `json:"smtp_username"`
 	SMTPPassword      string   `json:"smtp_password"`
 	SkipCertVerify    bool     `json:"smtp_skip_cert_verify"`
+	MaxEmailSize      int64    `json:"smtp_max_email_size"`
 	LocalListenIP     string   `json:"local_listen_ip"`
 	LocalListenPort   int      `json:"local_listen_port"`
 	AllowedHosts      []string `json:"allowed_hosts"`
+	TimeoutSecs       int      `json:"timeout_secs"`
 }
 
 func main() {
@@ -90,6 +100,8 @@ func run() error {
 
 func loadConfig(path string) (*mailRelayConfig, error) {
 	var cfg mailRelayConfig
+	configDefaults(&cfg)
+
 	file, err := os.Open(path)
 	if err != nil {
 		return nil, err
@@ -103,6 +115,18 @@ func loadConfig(path string) (*mailRelayConfig, error) {
 	return &cfg, nil
 }
 
+func configDefaults(config *mailRelayConfig) {
+	config.SMTPPort = DefaultSTMPPort
+	config.SMTPStartTLS = false
+	config.SMTPLoginAuthType = false
+	config.MaxEmailSize = DefaultMaxEmailSize
+	config.SkipCertVerify = false
+	config.LocalListenIP = DefaultLocalListenIP
+	config.LocalListenPort = DefaultLocalListenPort
+	config.AllowedHosts = []string{"*"}
+	config.TimeoutSecs = DefaultTimeoutSecs
+}
+
 // sendTest sends a test message to the SMTP server specified in mailrelay.json
 func sendTest(sender string, rcpt string, port int) error {
 	conn, err := smtp.Dial(fmt.Sprintf("localhost:%d", port))
diff --git a/server.go b/server.go
index fd861d7..cd9994f 100644
--- a/server.go
+++ b/server.go
@@ -9,7 +9,9 @@ import (
 	"github.com/flashmob/go-guerrilla/mail"
 )
 
-const saveWorkersSize = 3
+const (
+	saveWorkersSize = 3
+)
 
 // Start starts the server.
 func Start(appConfig *mailRelayConfig, verbose bool) (err error) {
@@ -28,6 +30,8 @@ func Start(appConfig *mailRelayConfig, verbose bool) (err error) {
 	sc := guerrilla.ServerConfig{
 		ListenInterface: listen,
 		IsEnabled:       true,
+		MaxSize:         appConfig.MaxEmailSize,
+		Timeout:         appConfig.TimeoutSecs,
 	}
 	cfg.Servers = append(cfg.Servers, sc)