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.idea

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# GNU LESSER GENERAL PUBLIC LICENSE
Version 3, 29 June 2007
Copyright (C) 2007 Free Software Foundation, Inc.
<https://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
This version of the GNU Lesser General Public License incorporates the
terms and conditions of version 3 of the GNU General Public License,
supplemented by the additional permissions listed below.
## 0. Additional Definitions.
As used herein, "this License" refers to version 3 of the GNU Lesser
General Public License, and the "GNU GPL" refers to version 3 of the
GNU General Public License.
"The Library" refers to a covered work governed by this License, other
than an Application or a Combined Work as defined below.
An "Application" is any work that makes use of an interface provided
by the Library, but which is not otherwise based on the Library.
Defining a subclass of a class defined by the Library is deemed a mode
of using an interface provided by the Library.
A "Combined Work" is a work produced by combining or linking an
Application with the Library. The particular version of the Library
with which the Combined Work was made is also called the "Linked
Version".
The "Minimal Corresponding Source" for a Combined Work means the
Corresponding Source for the Combined Work, excluding any source code
for portions of the Combined Work that, considered in isolation, are
based on the Application, and not on the Linked Version.
The "Corresponding Application Code" for a Combined Work means the
object code and/or source code for the Application, including any data
and utility programs needed for reproducing the Combined Work from the
Application, but excluding the System Libraries of the Combined Work.
## 1. Exception to Section 3 of the GNU GPL.
You may convey a covered work under sections 3 and 4 of this License
without being bound by section 3 of the GNU GPL.
## 2. Conveying Modified Versions.
If you modify a copy of the Library, and, in your modifications, a
facility refers to a function or data to be supplied by an Application
that uses the facility (other than as an argument passed when the
facility is invoked), then you may convey a copy of the modified
version:
- a) under this License, provided that you make a good faith effort
to ensure that, in the event an Application does not supply the
function or data, the facility still operates, and performs
whatever part of its purpose remains meaningful, or
- b) under the GNU GPL, with none of the additional permissions of
this License applicable to that copy.
## 3. Object Code Incorporating Material from Library Header Files.
The object code form of an Application may incorporate material from a
header file that is part of the Library. You may convey such object
code under terms of your choice, provided that, if the incorporated
material is not limited to numerical parameters, data structure
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(ten or fewer lines in length), you do both of the following:
- a) Give prominent notice with each copy of the object code that
the Library is used in it and that the Library and its use are
covered by this License.
- b) Accompany the object code with a copy of the GNU GPL and this
license document.
## 4. Combined Works.
You may convey a Combined Work under terms of your choice that, taken
together, effectively do not restrict modification of the portions of
the Library contained in the Combined Work and reverse engineering for
debugging such modifications, if you also do each of the following:
- a) Give prominent notice with each copy of the Combined Work that
the Library is used in it and that the Library and its use are
covered by this License.
- b) Accompany the Combined Work with a copy of the GNU GPL and this
license document.
- c) For a Combined Work that displays copyright notices during
execution, include the copyright notice for the Library among
these notices, as well as a reference directing the user to the
copies of the GNU GPL and this license document.
- d) Do one of the following:
- 0) Convey the Minimal Corresponding Source under the terms of
this License, and the Corresponding Application Code in a form
suitable for, and under terms that permit, the user to
recombine or relink the Application with a modified version of
the Linked Version to produce a modified Combined Work, in the
manner specified by section 6 of the GNU GPL for conveying
Corresponding Source.
- 1) Use a suitable shared library mechanism for linking with
the Library. A suitable mechanism is one that (a) uses at run
time a copy of the Library already present on the user's
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version of the Library that is interface-compatible with the
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- e) Provide Installation Information, but only if you would
otherwise be required to provide such information under section 6
of the GNU GPL, and only to the extent that such information is
necessary to install and execute a modified version of the
Combined Work produced by recombining or relinking the Application
with a modified version of the Linked Version. (If you use option
4d0, the Installation Information must accompany the Minimal
Corresponding Source and Corresponding Application Code. If you
use option 4d1, you must provide the Installation Information in
the manner specified by section 6 of the GNU GPL for conveying
Corresponding Source.)
## 5. Combined Libraries.
You may place library facilities that are a work based on the Library
side by side in a single library together with other library
facilities that are not Applications and are not covered by this
License, and convey such a combined library under terms of your
choice, if you do both of the following:
- a) Accompany the combined library with a copy of the same work
based on the Library, uncombined with any other library
facilities, conveyed under the terms of this License.
- b) Give prominent notice with the combined library that part of it
is a work based on the Library, and explaining where to find the
accompanying uncombined form of the same work.
## 6. Revised Versions of the GNU Lesser General Public License.
The Free Software Foundation may publish revised and/or new versions
of the GNU Lesser General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Library
as you received it specifies that a certain numbered version of the
GNU Lesser General Public License "or any later version" applies to
it, you have the option of following the terms and conditions either
of that published version or of any later version published by the
Free Software Foundation. If the Library as you received it does not
specify a version number of the GNU Lesser General Public License, you
may choose any version of the GNU Lesser General Public License ever
published by the Free Software Foundation.
If the Library as you received it specifies that a proxy can decide
whether future versions of the GNU Lesser General Public License shall
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Library.

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# SMTP
A comprehensive library for sending and receiving emails using the SMTP protocol, written in Go.
[![Go Report Card](https://goreportcard.com/badge/git.ailur.dev/ailur/smtp)](https://goreportcard.com/report/git.ailur.dev/ailur/smtp) [![Go Reference](https://pkg.go.dev/badge/git.ailur.dev/ailur/smtp.svg)](https://pkg.go.dev/git.ailur.dev/ailur/smtp)

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module smtp
go 1.23
require (
git.ailur.dev/ailur/spf v1.0.1
github.com/google/uuid v1.6.0
)

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git.ailur.dev/ailur/spf v1.0.1 h1:ApkuF2YsQJgUMo0I4cmQcHBERXZ+ZspOkqMe2lyaUfk=
git.ailur.dev/ailur/spf v1.0.1/go.mod h1:j+l6sReELJT3VCyAt/DgOfNqNYU/AvzJvj5vgLt3WGo=
github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=

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package smtp
import (
"errors"
"fmt"
"io"
"net"
"strconv"
"strings"
"crypto/tls"
"net/textproto"
"git.ailur.dev/ailur/spf"
"github.com/google/uuid"
)
var (
defaultCapabilities = []string{
"250-8BITMIME",
"250-ENHANCEDSTATUSCODES",
"250-SMTPUTF8",
"250 BINARYMIME",
}
queue = make(map[uuid.UUID]*MailQueueItem)
)
// MailQueueItem is a struct that represents an item in the mail queue
type MailQueueItem struct {
From *Address
To []*Address
Host string
}
// ViewMailQueue returns the current mail queue
func ViewMailQueue() map[uuid.UUID]*MailQueueItem {
return queue
}
// Address is a struct that represents an email address
type Address struct {
Name string
Address string
}
// Mail is a struct that represents an email
type Mail struct {
From *Address
To []*Address
Data []byte
}
// DatabaseBackend is a struct that represents a database backend
type DatabaseBackend struct {
CheckUser func(*Address) (bool, error)
WriteMail func(*Mail) (uuid.UUID, error)
}
// AuthenticationBackend is a struct that represents an authentication backend
type AuthenticationBackend struct {
Authenticate func(string) (*Address, error)
}
func readMultilineCodeResponse(conn *textproto.Conn) (int, string, error) {
var lines strings.Builder
for {
line, err := conn.ReadLine()
if err != nil {
return 0, "", err
}
lines.WriteString(line)
code, err := strconv.Atoi(line[:3])
if err != nil {
return 0, "", err
}
if line[3] != '-' {
return code, lines.String(), nil
}
}
}
func systemError(err error, receiver *Address, database DatabaseBackend) {
_, _ = database.WriteMail(&Mail{
From: &Address{
Name: "EMail System",
Address: "system",
},
To: []*Address{receiver},
Data: []byte(fmt.Sprintf("Hello there. This is the EMail system.\n We're sorry, but an error occurred while trying to send your email. The error was: %s. The email has not been sent.", err.Error())),
})
}
func sendEmail(args SenderArgs, mail *Mail, database DatabaseBackend, queueID uuid.UUID) {
mxs, err := net.LookupMX(mail.To[0].Address)
if err != nil {
systemError(err, queue[queueID].From, database)
delete(queue, queueID)
return
}
ips, err := net.LookupIP(mxs[0].Host)
if err != nil {
systemError(err, queue[queueID].From, database)
delete(queue, queueID)
return
}
conn, err := net.Dial("tcp", ips[0].String()+":25")
if err != nil {
systemError(err, queue[queueID].From, database)
delete(queue, queueID)
return
}
err = Send(args, mail, conn, mxs[0].Host)
if err != nil {
systemError(err, queue[queueID].From, database)
delete(queue, queueID)
return
}
err = conn.Close()
if err != nil {
systemError(err, queue[queueID].From, database)
delete(queue, queueID)
return
}
delete(queue, queueID)
}
func speakMultiLine(conn *textproto.Conn, lines []string) error {
for _, line := range lines {
err := conn.PrintfLine(line)
if err != nil {
return err
}
}
return nil
}
// Receiver is a struct that represents an SMTP receiver
type Receiver struct {
underlyingListener net.Listener
hostname string
ownedDomains map[string]any
enforceTLS bool
tlsConfig *tls.Config
database DatabaseBackend
auth AuthenticationBackend
}
// NewReceiver creates a new Receiver
func NewReceiver(conn net.Listener, hostname string, ownedDomains []string, enforceTLS bool, database DatabaseBackend, authentication AuthenticationBackend, tlsConfig *tls.Config) *Receiver {
var ownedDomainsMap = make(map[string]any)
for _, domain := range ownedDomains {
ownedDomainsMap[domain] = nil
}
return &Receiver{
underlyingListener: conn,
hostname: hostname,
ownedDomains: ownedDomainsMap,
enforceTLS: enforceTLS,
tlsConfig: tlsConfig,
database: database,
auth: authentication,
}
}
// Close closes the connection to the Receiver
func (fr *Receiver) Close() error {
return fr.underlyingListener.Close()
}
// Serve serves the Receiver. It will always return a non-nil error
func (fr *Receiver) Serve() error {
for {
conn, err := fr.underlyingListener.Accept()
if err != nil {
return err
}
go fr.handleConnection(conn)
}
}
func (fr *Receiver) handleConnection(conn net.Conn) {
var state struct {
HELO bool
AUTH *Address
TLS bool
FROM *Address
RCPT []*Address
DATA []byte
}
submissionSlice := strings.Split(conn.LocalAddr().String(), ":")
isSubmission := submissionSlice[len(submissionSlice)-1] != "25"
textProto := textproto.NewConn(conn)
err := textProto.PrintfLine("220 %s ESMTP At your service", fr.hostname)
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
fmt.Println("Connection from", conn.RemoteAddr().String())
for {
line, err := textProto.ReadLine()
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
switch {
case strings.HasPrefix(line, "QUIT"):
err = textProto.PrintfLine("221 2.0.0 See you soon")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
}
_ = conn.Close()
return
case strings.HasPrefix(line, "RSET"):
state.HELO = false
state.AUTH = nil
state.FROM = nil
state.RCPT = nil
state.DATA = nil
err = textProto.PrintfLine("250 2.0.0 Connection reset")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
case strings.HasPrefix(line, "NOOP"):
err = textProto.PrintfLine("250 2.0.0 Take your time")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
case strings.HasPrefix(line, "HELO"):
if state.HELO {
err = textProto.PrintfLine("503 5.5.1 HELO already called")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
} else {
state.HELO = true
err = textProto.PrintfLine("250 %s, ready to receive mail", fr.hostname)
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
}
case strings.HasPrefix(line, "EHLO"):
if state.HELO {
err = textProto.PrintfLine("503 5.5.1 EHLO already called")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
} else {
var capabilities []string
if fr.tlsConfig != nil {
capabilities = append(capabilities, "250-STARTTLS")
}
if fr.enforceTLS {
capabilities = append(capabilities, "250-REQUIRETLS")
}
capabilities = append(capabilities, defaultCapabilities...)
state.HELO = true
err = speakMultiLine(textProto, capabilities)
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
}
case strings.HasPrefix(line, "AUTH"):
if !isSubmission {
err = textProto.PrintfLine("503 5.5.1 AUTH only allowed on submission port")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
if !state.TLS && fr.enforceTLS {
err = textProto.PrintfLine("530 5.7.0 Must issue a STARTTLS command first")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
if state.AUTH != nil {
err = textProto.PrintfLine("503 5.5.1 AUTH already called")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
} else {
address, err := fr.auth.Authenticate(line)
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
if address == nil {
err = textProto.PrintfLine("535 5.7.8 Authentication failed")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
} else {
state.AUTH = address
err = textProto.PrintfLine("235 2.7.0 Authentication successful")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
}
}
case strings.HasPrefix(line, "STARTTLS"):
if state.TLS {
err = textProto.PrintfLine("503 5.5.1 STARTTLS already called")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
} else {
err = textProto.PrintfLine("220 2.0.0 Ready to start TLS")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
tlsConn := tls.Server(conn, fr.tlsConfig)
textProto = textproto.NewConn(tlsConn)
state.HELO = false
state.AUTH = nil
state.FROM = nil
state.RCPT = nil
state.DATA = nil
state.TLS = true
}
case strings.HasPrefix(line, "MAIL FROM"):
if !state.HELO {
err = textProto.PrintfLine("503 5.5.1 HELO required")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
if !state.TLS && fr.enforceTLS {
err = textProto.PrintfLine("530 5.7.0 Must issue a STARTTLS command first")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
addressSlice := strings.Split(strings.TrimPrefix(strings.TrimSuffix(line, ">"), "MAIL FROM:<"), "@")
address := &Address{
Name: addressSlice[0],
Address: addressSlice[1],
}
if isSubmission {
if state.AUTH == nil {
err = textProto.PrintfLine("503 5.5.1 AUTH required")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
if *address != *state.AUTH {
err = textProto.PrintfLine("535 5.7.8 Authenticated wrong user")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
} else {
err := spf.CheckIP(strings.Split(conn.RemoteAddr().String(), ":")[0], address.Address)
if err != nil {
if err.Type() == spf.ErrTypeInternal {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
} else {
err := textProto.PrintfLine("550 5.7.1 SPF check failed")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
}
}
state.FROM = address
err = textProto.PrintfLine("250 2.1.0 Sender OK")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
case strings.HasPrefix(line, "RCPT TO"):
if !state.TLS && fr.enforceTLS {
err = textProto.PrintfLine("530 5.7.0 Must issue a STARTTLS command first")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
addressSlice := strings.Split(strings.TrimPrefix(strings.TrimSuffix(line, ">"), "RCPT TO:<"), "@")
address := &Address{
Name: addressSlice[0],
Address: addressSlice[1],
}
if isSubmission {
if state.AUTH == nil {
err = textProto.PrintfLine("503 5.5.1 AUTH required")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
} else {
_, ok := fr.ownedDomains[address.Address]
if !ok {
err = textProto.PrintfLine("503 5.5.1 Relaying not allowed")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
ok, err := fr.database.CheckUser(address)
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
if !ok {
err = textProto.PrintfLine("550 5.1.1 User not found")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
}
state.RCPT = append(state.RCPT, address)
err = textProto.PrintfLine("250 2.1.5 Recipient OK")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
case strings.HasPrefix(line, "DATA"):
if !state.TLS && fr.enforceTLS {
err = textProto.PrintfLine("530 5.7.0 Must issue a STARTTLS command first")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
if state.FROM == nil {
err = textProto.PrintfLine("503 5.5.1 MAIL FROM required")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
if len(state.RCPT) == 0 {
err = textProto.PrintfLine("503 5.5.1 RCPT TO required")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
continue
}
err = textProto.PrintfLine("354 2.0.0 Start mail input; end with <CRLF>.<CRLF>")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
state.DATA, err = io.ReadAll(textProto.DotReader())
mail := &Mail{
From: state.FROM,
To: state.RCPT,
Data: state.DATA,
}
if !isSubmission {
_, err := fr.database.WriteMail(mail)
if err != nil {
_ = textProto.PrintfLine(err.Error())
_ = conn.Close()
return
}
err = textProto.PrintfLine("250 2.0.0 Message accepted for delivery")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
} else {
queueID := uuid.New()
queue[queueID] = &MailQueueItem{
From: state.FROM,
To: state.RCPT,
Host: strings.Split(conn.RemoteAddr().String(), ":")[0],
}
go sendEmail(SenderArgs{
Hostname: fr.hostname,
EnforceTLS: fr.enforceTLS,
}, mail, fr.database, queueID)
err = textProto.PrintfLine("250 2.0.0 Message queued for delivery")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
state.DATA = nil
state.FROM = nil
state.RCPT = nil
}
default:
err = textProto.PrintfLine("500 5.5.2 Command not recognized")
if err != nil {
_ = textProto.PrintfLine("421 4.7.0 Temporary server error")
_ = conn.Close()
return
}
}
}
}
// SenderArgs is a struct that represents the arguments for the Sender
type SenderArgs struct {
Hostname string
EnforceTLS bool
}
// Send sends an email to another server
func Send(args SenderArgs, mail *Mail, conn net.Conn, mxHost string) (err error) {
textConn := textproto.NewConn(conn)
err = textConn.PrintfLine("RSET")
if err != nil {
return err
}
code, line, err := textConn.ReadCodeLine(0)
if err != nil {
return err
}
if code != 220 {
return errors.New("unexpected RSET response - " + line)
}
code, line, err = textConn.ReadCodeLine(0)
if err != nil {
return err
}
if code != 250 {
return errors.New("unexpected greeting - " + line)
}
err = textConn.PrintfLine("EHLO %s", args.Hostname)
if err != nil {
return err
}
code, lines, err := readMultilineCodeResponse(textConn)
if err != nil {
return err
}
if code != 250 {
return errors.New("unexpected EHLO response - " + lines)
}
if strings.Contains(lines, "STARTTLS") {
err = textConn.PrintfLine("STARTTLS")
if err != nil {
return err
}
code, line, err := textConn.ReadCodeLine(0)
if err != nil {
return err
}
if code != 220 {
return errors.New("unexpected STARTTLS response - " + line)
}
tlsConn := tls.Client(conn, &tls.Config{
ServerName: mxHost,
InsecureSkipVerify: false,
})
err = tlsConn.Handshake()
if err != nil {
return err
}
textConn = textproto.NewConn(tlsConn)
// Just use HELO, no point using EHLO when we already have all the capabilities
// This also gets us out of using readMultilineCodeResponse
err = textConn.PrintfLine("HELO %s", args.Hostname)
if err != nil {
return err
}
code, line, err = textConn.ReadCodeLine(0)
if err != nil {
return err
}
if code != 250 {
return errors.New("unexpected STARTTLS HELO response - " + line)
}
} else if args.EnforceTLS {
return errors.New("STARTTLS not supported")
}
err = textConn.PrintfLine("MAIL FROM:<%s@%s>", mail.From.Name, mail.From.Address)
if err != nil {
return err
}
code, line, err = textConn.ReadCodeLine(0)
fmt.Println(code, line, err)
if err != nil {
// For some reason the EHLO stuff ends up here
fmt.Println("5")
return err
}
if code != 250 {
return errors.New("unexpected MAIL FROM response - " + line)
}
for _, recipient := range mail.To {
err = textConn.PrintfLine("RCPT TO:<%s@%s>", recipient.Name, recipient.Address)
if err != nil {
return err
}
code, line, err = textConn.ReadCodeLine(0)
fmt.Println(code, line, err)
if err != nil {
fmt.Println("6")
return err
}
if code != 250 {
return errors.New("unexpected RCPT TO response - " + line)
}
}
err = textConn.PrintfLine("DATA")
if err != nil {
return err
}
code, line, err = textConn.ReadCodeLine(0)
fmt.Println(code, line, err)
if err != nil {
fmt.Println("7")
return err
}
if code != 354 {
return errors.New("unexpected DATA response - " + line)
}
writer := textConn.DotWriter()
_, err = writer.Write(mail.Data)
if err != nil {
return err
}
err = writer.Close()
if err != nil {
return errors.New("failed to close data writer - " + err.Error())
}
code, line, err = textConn.ReadCodeLine(0)
fmt.Println(code, line, err)
if err != nil {
fmt.Println("8")
return err
}
if code != 250 {
return errors.New("unexpected DATA finish response - " + line + ", your message may have been sent, but it is not guaranteed")
}
err = textConn.PrintfLine("QUIT")
if err != nil {
return err
}
code, line, err = textConn.ReadCodeLine(0)
fmt.Println(code, line, err)
if err != nil {
fmt.Println("9")
return err
}
if code != 221 {
return errors.New("unexpected QUIT response - " + line + ", your message may have been sent, but it is not guaranteed")
}
return
}