Update Go version to 1.22 for release builds

Bumps [golang.org/x/crypto](https://github.com/golang/crypto) from 0.21.0 to 0.22.0.
- [Commits](https://github.com/golang/crypto/compare/v0.21.0...v0.22.0)

---
updated-dependencies:
- dependency-name: golang.org/x/crypto
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/codeql-analysis.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.
@@ -38,7 +38,7 @@ jobs:
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v2
+      uses: github/codeql-action/init@v3
       with:
         languages: ${{ matrix.language }}
         # If you wish to specify custom queries, you can do so here or in a config file.
@@ -49,7 +49,7 @@ jobs:
     # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
     # If this step fails, then you should remove it and run the build manually (see below)
     - name: Autobuild
-      uses: github/codeql-action/autobuild@v2
+      uses: github/codeql-action/autobuild@v3
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
@@ -63,4 +63,4 @@ jobs:
     #   make release
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v2
+      uses: github/codeql-action/analyze@v3

.github/workflows/go.yml

@@ -6,19 +6,13 @@ jobs:
     name: Build
     runs-on: ubuntu-latest
     steps:
-
+    - uses: actions/checkout@v4
-    - name: Set up Go 1.18
+    - uses: actions/setup-go@v5
-      uses: actions/setup-go@v3
       with:
-        go-version: 1.18
+        go-version: 'stable'
-      id: go
-
-    - name: Check out code into the Go module directory
-      uses: actions/checkout@v3
-
-    - name: Get dependencies
-      run: |
-        go get -v -t -d ./...
 
     - name: Build
       run: go build -v .
+
+    - name: Test
+      run: go test -v .

.github/workflows/release.yaml

@@ -13,18 +13,18 @@ jobs:
         goos: [freebsd, linux, windows]
         goarch: [amd64, arm64]
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     
     - name: Set APP_VERSION env
       run: echo APP_VERSION=$(echo ${GITHUB_REF} | rev | cut -d'/' -f 1 | rev ) >> ${GITHUB_ENV}
     - name: Set BUILD_TIME env
       run: echo BUILD_TIME=$(date) >> ${GITHUB_ENV}
       
-    - uses: wangyoucao577/go-release-action@v1.28
+    - uses: wangyoucao577/go-release-action@v1
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}
         goos: ${{ matrix.goos }}
         goarch: ${{ matrix.goarch }}
-        goversion: 1.18
+        goversion: "1.22"
         extra_files: LICENSE README.md smtprelay.ini
         ldflags: -s -w -X "main.appVersion=${{ env.APP_VERSION }}" -X "main.buildTime=${{ env.BUILD_TIME }}"

README.md

@@ -22,6 +22,7 @@ device which produces mail.
 
 ## Main features
 
+* Simple configuration with ini file .env file or environment variables
 * Supports SMTPS/TLS (465), STARTTLS (587) and unencrypted SMTP (25)
 * Checks for sender, receiver, client IP
 * Authentication support with file (LOGIN, PLAIN)

config.go

@@ -1,15 +1,18 @@
 package main
 
 import (
+	"bufio"
 	"flag"
 	"fmt"
+	"io"
 	"net"
+	"os"
 	"regexp"
 	"strings"
 	"time"
 
+	"github.com/peterbourgon/ff/v3"
 	"github.com/sirupsen/logrus"
-	"github.com/vharitonsky/iniflags"
 )
 
 var (
@@ -18,36 +21,45 @@ var (
 )
 
 var (
-	logFile           = flag.String("logfile", "", "Path to logfile")
+	flagset = flag.NewFlagSet("smtprelay", flag.ContinueOnError)
-	logFormat         = flag.String("log_format", "default", "Log output format")
+
-	logLevel          = flag.String("log_level", "info", "Minimum log level to output")
+	// config flags
-	hostName          = flag.String("hostname", "localhost.localdomain", "Server hostname")
+	logFile          = flagset.String("logfile", "", "Path to logfile")
-	welcomeMsg        = flag.String("welcome_msg", "", "Welcome message for SMTP session")
+	logFormat        = flagset.String("log_format", "default", "Log output format")
-	listenStr         = flag.String("listen", "127.0.0.1:25 [::1]:25", "Address and port to listen for incoming SMTP")
+	logLevel         = flagset.String("log_level", "info", "Minimum log level to output")
+	hostName         = flagset.String("hostname", "localhost.localdomain", "Server hostname")
+	welcomeMsg       = flagset.String("welcome_msg", "", "Welcome message for SMTP session")
+	listenStr        = flagset.String("listen", "127.0.0.1:25 [::1]:25", "Address and port to listen for incoming SMTP")
+	localCert        = flagset.String("local_cert", "", "SSL certificate for STARTTLS/TLS")
+	localKey         = flagset.String("local_key", "", "SSL private key for STARTTLS/TLS")
+	localForceTLS    = flagset.Bool("local_forcetls", false, "Force STARTTLS (needs local_cert and local_key)")
+	readTimeoutStr   = flagset.String("read_timeout", "60s", "Socket timeout for read operations")
+	writeTimeoutStr  = flagset.String("write_timeout", "60s", "Socket timeout for write operations")
+	dataTimeoutStr   = flagset.String("data_timeout", "5m", "Socket timeout for DATA command")
+	maxConnections   = flagset.Int("max_connections", 100, "Max concurrent connections, use -1 to disable")
+	maxMessageSize   = flagset.Int("max_message_size", 10240000, "Max message size in bytes")
+	maxRecipients    = flagset.Int("max_recipients", 100, "Max RCPT TO calls for each envelope")
+	allowedNetsStr   = flagset.String("allowed_nets", "127.0.0.0/8 ::1/128", "Networks allowed to send mails")
+	allowedSenderStr = flagset.String("allowed_sender", "", "Regular expression for valid FROM EMail addresses")
+	allowedRecipStr  = flagset.String("allowed_recipients", "", "Regular expression for valid TO EMail addresses")
+	allowedUsers     = flagset.String("allowed_users", "", "Path to file with valid users/passwords")
+	command          = flagset.String("command", "", "Path to pipe command")
+	remotesStr       = flagset.String("remotes", "", "Outgoing SMTP servers")
+	strictSender     = flagset.Bool("strict_sender", false, "Use only SMTP servers with Sender matches to From")
+
+	// additional flags
+	_           = flagset.String("config", "", "Path to config file (ini format)")
+	versionInfo = flagset.Bool("version", false, "Show version information")
+
+	// internal
 	listenAddrs       = []protoAddr{}
-	localCert         = flag.String("local_cert", "", "SSL certificate for STARTTLS/TLS")
-	localKey          = flag.String("local_key", "", "SSL private key for STARTTLS/TLS")
-	localForceTLS     = flag.Bool("local_forcetls", false, "Force STARTTLS (needs local_cert and local_key)")
-	readTimeoutStr    = flag.String("read_timeout", "60s", "Socket timeout for read operations")
 	readTimeout       time.Duration
-	writeTimeoutStr   = flag.String("write_timeout", "60s", "Socket timeout for write operations")
 	writeTimeout      time.Duration
-	dataTimeoutStr    = flag.String("data_timeout", "5m", "Socket timeout for DATA command")
 	dataTimeout       time.Duration
-	maxConnections    = flag.Int("max_connections", 100, "Max concurrent connections, use -1 to disable")
-	maxMessageSize    = flag.Int("max_message_size", 10240000, "Max message size in bytes")
-	maxRecipients     = flag.Int("max_recipients", 100, "Max RCPT TO calls for each envelope")
-	allowedNetsStr    = flag.String("allowed_nets", "127.0.0.0/8 ::1/128", "Networks allowed to send mails")
 	allowedNets       = []*net.IPNet{}
-	allowedSenderStr  = flag.String("allowed_sender", "", "Regular expression for valid FROM EMail addresses")
 	allowedSender     *regexp.Regexp
-	allowedRecipStr   = flag.String("allowed_recipients", "", "Regular expression for valid TO EMail addresses")
 	allowedRecipients *regexp.Regexp
-	allowedUsers      = flag.String("allowed_users", "", "Path to file with valid users/passwords")
-	command           = flag.String("command", "", "Path to pipe command")
-	remotesStr        = flag.String("remotes", "", "Outgoing SMTP servers")
 	remotes           = []*Remote{}
-	versionInfo       = flag.Bool("version", false, "Show version information")
 )
 
 func localAuthRequired() bool {
@@ -183,11 +195,36 @@ func setupTimeouts() {
 }
 
 func ConfigLoad() {
-	iniflags.Parse()
+	// use .env file if it exists
+	if _, err := os.Stat(".env"); err == nil {
+		if err := ff.Parse(flagset, os.Args[1:],
+			ff.WithEnvVarPrefix("smtprelay"),
+			ff.WithConfigFile(".env"),
+			ff.WithConfigFileParser(ff.EnvParser),
+		); err != nil {
+			fmt.Fprintf(os.Stderr, "error: %v\n", err)
+			os.Exit(1)
+		}
+	} else {
+		// use env variables and smtprelay.ini file
+		if err := ff.Parse(flagset, os.Args[1:],
+			ff.WithEnvVarPrefix("smtprelay"),
+			ff.WithConfigFileFlag("config"),
+			ff.WithConfigFileParser(IniParser),
+		); err != nil {
+			fmt.Fprintf(os.Stderr, "error: %v\n", err)
+			os.Exit(1)
+		}
+	}
 
 	// Set up logging as soon as possible
 	setupLogger()
 
+	if *versionInfo {
+		fmt.Printf("smtprelay/%s (%s)\n", appVersion, buildTime)
+		os.Exit(0)
+	}
+
 	if *remotesStr == "" && *command == "" {
 		log.Warn("no remotes or command set; mail will not be forwarded!")
 	}
@@ -198,3 +235,42 @@ func ConfigLoad() {
 	setupListeners()
 	setupTimeouts()
 }
+
+// IniParser is a parser for config files in classic key/value style format. Each
+// line is tokenized as a single key/value pair. The first "=" delimited
+// token in the line is interpreted as the flag name, and all remaining tokens
+// are interpreted as the value. Any leading hyphens on the flag name are
+// ignored.
+func IniParser(r io.Reader, set func(name, value string) error) error {
+	s := bufio.NewScanner(r)
+	for s.Scan() {
+		line := strings.TrimSpace(s.Text())
+		if line == "" {
+			continue // skip empties
+		}
+
+		if line[0] == '#' || line[0] == ';' {
+			continue // skip comments
+		}
+
+		var (
+			name  string
+			value string
+			index = strings.IndexRune(line, '=')
+		)
+		if index < 0 {
+			name, value = line, "true" // boolean option
+		} else {
+			name, value = strings.TrimSpace(line[:index]), strings.Trim(strings.TrimSpace(line[index+1:]), "\"")
+		}
+
+		if i := strings.Index(value, " #"); i >= 0 {
+			value = strings.TrimSpace(value[:i])
+		}
+
+		if err := set(name, value); err != nil {
+			return err
+		}
+	}
+	return nil
+}

go.mod

@@ -2,18 +2,20 @@ module github.com/decke/smtprelay
 
 require (
 	github.com/chrj/smtpd v0.3.1
-	github.com/google/uuid v1.3.0
+	github.com/google/uuid v1.6.0
-	github.com/sirupsen/logrus v1.8.1
+	github.com/peterbourgon/ff/v3 v3.4.0
-	github.com/stretchr/testify v1.7.1
+	github.com/sirupsen/logrus v1.9.3
-	github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de
+	github.com/stretchr/testify v1.9.0
-	golang.org/x/crypto v0.0.0-20220411220226-7b82a4e95df4
+	golang.org/x/crypto v0.23.0
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/kr/pretty v0.3.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/sys v0.0.0-20220422013727-9388b58f7150 // indirect
+	golang.org/x/sys v0.20.0 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
-go 1.18
+go 1.20

go.sum

@@ -1,26 +1,39 @@
 github.com/chrj/smtpd v0.3.1 h1:kogHFkbFdKaoH3bgZkqNC9uVtKYOFfM3uV3rroBdooE=
 github.com/chrj/smtpd v0.3.1/go.mod h1:JtABvV/LzvLmEIzy0NyDnrfMGOMd8wy5frAokwf6J9Q=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
-github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/peterbourgon/ff/v3 v3.4.0 h1:QBvM/rizZM1cB0p0lGMdmR7HxZeI/ZrBWB4DqLkMUBc=
+github.com/peterbourgon/ff/v3 v3.4.0/go.mod h1:zjJVUhx+twciwfDl0zBcFzl4dW8axCRyXE/eKY9RztQ=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=
+github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
-github.com/sirupsen/logrus v1.8.1/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
+github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de h1:fkw+7JkxF3U1GzQoX9h69Wvtvxajo5Rbzy6+YMMzPIg=
+golang.org/x/crypto v0.23.0 h1:dIJU/v2J8Mdglj/8rJ6UUOM3Zc9zLZxVZwwxMooUSAI=
-github.com/vharitonsky/iniflags v0.0.0-20180513140207-a33cd0b5f3de/go.mod h1:irMhzlTz8+fVFj6CH2AN2i+WI5S6wWFtK3MBCIxIpyI=
+golang.org/x/crypto v0.23.0/go.mod h1:CKFgDieR+mRhux2Lsu27y0fO304Db0wZe70UKqHu0v8=
-golang.org/x/crypto v0.0.0-20220411220226-7b82a4e95df4 h1:kUhD7nTDoI3fVd9G4ORWrbV5NY0liEs/Jg2pv5f+bBA=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/crypto v0.0.0-20220411220226-7b82a4e95df4/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
+golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
-golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/sys v0.0.0-20220422013727-9388b58f7150 h1:xHms4gcpe1YE7A3yIllJXP16CMAGuqwO2lX1mTyyRRc=
-golang.org/x/sys v0.0.0-20220422013727-9388b58f7150/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -164,9 +164,21 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 		"uuid": generateUUID(),
 	})
 
-	if *remotesStr == "" && *command == "" {
+	var envRemotes []*Remote
+
+	if *strictSender {
+		for _, remote := range remotes {
+			if remote.Sender == env.Sender {
+				envRemotes = append(envRemotes, remote)
+			}
+		}
+	} else {
+		envRemotes = remotes
+	}
+
+	if len(envRemotes) == 0 && *command == "" {
 		logger.Warning("no remote_host or command set; discarding mail")
-		return nil
+		return smtpd.Error{Code: 554, Message: "There are no appropriate remote_host or command"}
 	}
 
 	env.AddReceivedLine(peer)
@@ -177,7 +189,16 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 		var stdout bytes.Buffer
 		var stderr bytes.Buffer
 
-		cmd := exec.Command(*command)
+		environ := os.Environ()
+		environ = append(environ, fmt.Sprintf("%s=%s", "SMTPRELAY_FROM", env.Sender))
+		environ = append(environ, fmt.Sprintf("%s=%s", "SMTPRELAY_TO", env.Recipients))
+		environ = append(environ, fmt.Sprintf("%s=%s", "SMTPRELAY_PEER", peerIP))
+
+		cmd := exec.Cmd{
+			Env: environ,
+			Path: *command,
+		}
+
 		cmd.Stdin = bytes.NewReader(env.Data)
 		cmd.Stdout = &stdout
 		cmd.Stderr = &stderr
@@ -191,7 +212,7 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 		cmdLogger.Info("pipe command successful: " + stdout.String())
 	}
 
-	for _, remote := range remotes {
+	for _, remote := range envRemotes {
 		logger = logger.WithField("host", remote.Addr)
 		logger.Info("delivering mail from peer using smarthost")
 
@@ -282,11 +303,6 @@ func getTLSConfig() *tls.Config {
 func main() {
 	ConfigLoad()
 
-	if *versionInfo {
-		fmt.Printf("smtprelay/%s (%s)\n", appVersion, buildTime)
-		os.Exit(0)
-	}
-
 	log.WithField("version", appVersion).
 		Debug("starting smtprelay")
 

remotes.go

@@ -25,7 +25,6 @@ type Remote struct {
 // Supported Params:
 // - skipVerify: can be "true" or empty to prevent ssl verification of remote server's certificate.
 // - auth: can be "login" to trigger "LOGIN" auth instead of "PLAIN" auth
-//
 func ParseRemote(remoteURL string) (*Remote, error) {
 	u, err := url.Parse(remoteURL)
 	if err != nil {

smtprelay.ini

@@ -1,19 +1,23 @@
 ; smtprelay configuration
+;
+; All config parameters can also be provided as environment
+; variables in uppercase and the prefix "SMTPRELAY_".
+; (eg. SMTPRELAY_LOGFILE, SMTPRELAY_LOG_FORMAT)
 
 ; Logfile (blank/default is stderr)
 ;logfile = 
 
 ; Log format: default, plain (no timestamp), json
-;log_format = "default"
+;log_format = default
 
 ; Log level: panic, fatal, error, warn, info, debug, trace
-;log_level = "info"
+;log_level = info
 
 ; Hostname for this SMTP server
-;hostname = "localhost.localdomain"
+;hostname = localhost.localdomain
 
 ; Welcome message for clients
-;welcome_msg = "<hostname> ESMTP ready."
+;welcome_msg = <hostname> ESMTP ready.
 
 ; Listen on the following addresses for incoming
 ; unencrypted connections.
@@ -30,6 +34,10 @@
 ; accepting mails from client.
 ;local_forcetls = false
 
+; Only use remotes where FROM EMail address in received
+; EMail matches remote_sender.
+;strict_sender = false
+
 ; Socket timeout for read operations
 ; Duration string as sequence of decimal numbers,
 ; each with optional fraction and a unit suffix.