diff --git a/README.md b/README.md
index f9ea46b912..865d3284c2 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ Mailpit is inspired by [MailHog](#why-rewrite-mailhog), but much, much faster.
- Configurable automatic email pruning (default keeps the most recent 500 emails)
- Email storage either in a temporary or persistent database ([see wiki](https://github.com/axllent/mailpit/wiki/Email-storage))
- Fast SMTP processing & storing - approximately 70-100 emails per second depending on CPU, network speed & email size, easily handling tens of thousands of emails
-- SMTP relaying / message release - relay messages via a different SMTP server ([see wiki](https://github.com/axllent/mailpit/wiki/SMTP-relay))
+- SMTP relaying / message release - relay messages via a different SMTP server including a allowlist of accepted recipients ([see wiki](https://github.com/axllent/mailpit/wiki/SMTP-relay))
- Optional SMTP with STARTTLS & SMTP authentication, including an "accept anything" mode ([see wiki](https://github.com/axllent/mailpit/wiki/SMTP-with-STARTTLS-and-authentication))
- Optional HTTPS for web UI ([see wiki](https://github.com/axllent/mailpit/wiki/HTTPS))
- Optional basic authentication for web UI ([see wiki](https://github.com/axllent/mailpit/wiki/Basic-authentication))
diff --git a/config/config.go b/config/config.go
index de65bab74d..dbc9a82534 100644
--- a/config/config.go
+++ b/config/config.go
@@ -111,15 +111,17 @@ type AutoTag struct {
// SMTPRelayConfigStruct struct for parsing yaml & storing variables
type smtpRelayConfigStruct struct {
- Host string `yaml:"host"`
- Port int `yaml:"port"`
- STARTTLS bool `yaml:"starttls"`
- AllowInsecure bool `yaml:"allow-insecure"`
- Auth string `yaml:"auth"` // none, plain, cram-md5
- Username string `yaml:"username"` // plain & cram-md5
- Password string `yaml:"password"` // plain
- Secret string `yaml:"secret"` // cram-md5
- ReturnPath string `yaml:"return-path"` // allows overriding the boune address
+ Host string `yaml:"host"`
+ Port int `yaml:"port"`
+ STARTTLS bool `yaml:"starttls"`
+ AllowInsecure bool `yaml:"allow-insecure"`
+ Auth string `yaml:"auth"` // none, plain, cram-md5
+ Username string `yaml:"username"` // plain & cram-md5
+ Password string `yaml:"password"` // plain
+ Secret string `yaml:"secret"` // cram-md5
+ ReturnPath string `yaml:"return-path"` // allows overriding the boune address
+ RecipientAllowlist string `yaml:"recipient-allowlist"` // regex, if set needs to match for mails to be relayed
+ RecipientAllowlistRegexp *regexp.Regexp
}
// VerifyConfig wil do some basic checking
@@ -296,6 +298,18 @@ func parseRelayConfig(c string) error {
logger.Log().Infof("[smtp] enabling message relaying via %s:%d", SMTPRelayConfig.Host, SMTPRelayConfig.Port)
+ allowlistRegexp, err := regexp.Compile(SMTPRelayConfig.RecipientAllowlist)
+
+ if SMTPRelayConfig.RecipientAllowlist != "" {
+ if err != nil {
+ return fmt.Errorf("failed to compile recipient allowlist regexp: %e", err)
+ }
+
+ SMTPRelayConfig.RecipientAllowlistRegexp = allowlistRegexp
+ logger.Log().Infof("[smtp] recipient allowlist is active with the following regexp: %s", SMTPRelayConfig.RecipientAllowlist)
+
+ }
+
return nil
}
diff --git a/server/apiv1/api.go b/server/apiv1/api.go
index 260d6db52c..b1a019db3d 100644
--- a/server/apiv1/api.go
+++ b/server/apiv1/api.go
@@ -554,10 +554,17 @@ func ReleaseMessage(w http.ResponseWriter, r *http.Request) {
}
for _, to := range tos {
- if _, err := mail.ParseAddress(to); err != nil {
+ address, err := mail.ParseAddress(to)
+
+ if err != nil {
httpError(w, "Invalid email address: "+to)
return
}
+
+ if config.SMTPRelayConfig.RecipientAllowlistRegexp != nil && !config.SMTPRelayConfig.RecipientAllowlistRegexp.MatchString(address.Address) {
+ httpError(w, "Mail address does not match allowlist: "+to)
+ return
+ }
}
reader := bytes.NewReader(msg)
diff --git a/server/apiv1/webui.go b/server/apiv1/webui.go
index 60c0a39b71..c586944469 100644
--- a/server/apiv1/webui.go
+++ b/server/apiv1/webui.go
@@ -20,6 +20,8 @@ type webUIConfiguration struct {
SMTPServer string
// Enforced Return-Path (if set) for relay bounces
ReturnPath string
+ // Allowlist of accepted recipients
+ RecipientAllowlist string
}
}
@@ -45,6 +47,7 @@ func WebUIConfig(w http.ResponseWriter, r *http.Request) {
if config.ReleaseEnabled {
conf.MessageRelay.SMTPServer = fmt.Sprintf("%s:%d", config.SMTPRelayConfig.Host, config.SMTPRelayConfig.Port)
conf.MessageRelay.ReturnPath = config.SMTPRelayConfig.ReturnPath
+ conf.MessageRelay.RecipientAllowlist = config.SMTPRelayConfig.RecipientAllowlist
}
bytes, _ := json.Marshal(conf)
diff --git a/server/smtpd/smtp.go b/server/smtpd/smtp.go
index 34eaac3e5a..7f2c3bacbe 100644
--- a/server/smtpd/smtp.go
+++ b/server/smtpd/smtp.go
@@ -3,13 +3,45 @@ package smtpd
import (
"crypto/tls"
"fmt"
- "net/smtp"
-
"github.com/axllent/mailpit/config"
+ "github.com/axllent/mailpit/utils/logger"
+ "net/mail"
+ "net/smtp"
)
+func allowedRecipients(to []string) []string {
+ if config.SMTPRelayConfig.RecipientAllowlistRegexp == nil {
+ return to
+ }
+
+ var ar []string
+
+ for _, recipient := range to {
+ address, err := mail.ParseAddress(recipient)
+
+ if err != nil {
+ logger.Log().Warnf("ignoring invalid email address: %s", recipient)
+ continue
+ }
+
+ if !config.SMTPRelayConfig.RecipientAllowlistRegexp.MatchString(address.Address) {
+ logger.Log().Debugf("[smtp] not allowed to relay to %s: does not match the allowlist %s", recipient, config.SMTPRelayConfig.RecipientAllowlist)
+ } else {
+ ar = append(ar, recipient)
+ }
+ }
+
+ return ar
+}
+
// Send will connect to a pre-configured SMTP server and send a message to one or more recipients.
func Send(from string, to []string, msg []byte) error {
+ recipients := allowedRecipients(to)
+
+ if len(recipients) == 0 {
+ return nil
+ }
+
addr := fmt.Sprintf("%s:%d", config.SMTPRelayConfig.Host, config.SMTPRelayConfig.Port)
c, err := smtp.Dial(addr)
@@ -48,7 +80,7 @@ func Send(from string, to []string, msg []byte) error {
return err
}
- for _, addr := range to {
+ for _, addr := range recipients {
if err = c.Rcpt(addr); err != nil {
return err
}
diff --git a/server/ui-src/templates/MessageRelease.vue b/server/ui-src/templates/MessageRelease.vue
index 2ac453200b..6c4e019de9 100644
--- a/server/ui-src/templates/MessageRelease.vue
+++ b/server/ui-src/templates/MessageRelease.vue
@@ -83,6 +83,11 @@ export default {
Invalid email address
+
+ Note: A recipient allowlist has been configured. Any mail address not matching it will be rejected.
+
+ Configured allowlist: {{ relayConfig.MessageRelay.RecipientAllowlist }}
+
Note: For testing purposes, a unique Message-Id will be generated on send.
diff --git a/storage/database.go b/storage/database.go
index 3c4637fd43..d4ec9265a3 100644
--- a/storage/database.go
+++ b/storage/database.go
@@ -470,7 +470,7 @@ func GetMessage(id string) (*Message, error) {
messageID := strings.Trim(env.GetHeader("Message-ID"), "<>")
returnPath := strings.Trim(env.GetHeader("Return-Path"), "<>")
- if returnPath == "" {
+ if returnPath == "" && from != nil {
returnPath = from.Address
}