Adjusting license headers and including original LICENSE file from the Go project into the smtp/ directory as suggested in https://github.com/wneessen/go-mail/issues/97#issuecomment-1381046444

smtp/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

smtp/auth.go

@@ -3,7 +3,7 @@
 //
 // Original net/smtp code from the Go stdlib by the Go Authors.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the [PROJECT ROOT]/LICENSES directory.
+// LICENSE file that can be found in this directory.
 //
 // go-mail specific modifications by the go-mail Authors.
 // Licensed under the MIT License.

smtp/auth_cram_md5.go

@@ -3,7 +3,7 @@
 //
 // Original net/smtp code from the Go stdlib by the Go Authors.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the [PROJECT ROOT]/LICENSES directory.
+// LICENSE file that can be found in this directory.
 //
 // go-mail specific modifications by the go-mail Authors.
 // Licensed under the MIT License.
@@ -32,7 +32,7 @@ func CRAMMD5Auth(username, secret string) Auth {
 	return &cramMD5Auth{username, secret}
 }
 
-func (a *cramMD5Auth) Start(server *ServerInfo) (string, []byte, error) {
+func (a *cramMD5Auth) Start(_ *ServerInfo) (string, []byte, error) {
 	return "CRAM-MD5", nil, nil
 }
 

smtp/auth_login.go

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022 Winni Neessen <winni@neessen.dev>
+// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors
 //
 // SPDX-License-Identifier: MIT
 

smtp/auth_plain.go

@@ -3,7 +3,7 @@
 //
 // Original net/smtp code from the Go stdlib by the Go Authors.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the [PROJECT ROOT]/LICENSES directory.
+// LICENSE file that can be found in this directory.
 //
 // go-mail specific modifications by the go-mail Authors.
 // Licensed under the MIT License.
@@ -51,7 +51,7 @@ func (a *plainAuth) Start(server *ServerInfo) (string, []byte, error) {
 	return "PLAIN", resp, nil
 }
 
-func (a *plainAuth) Next(fromServer []byte, more bool) ([]byte, error) {
+func (a *plainAuth) Next(_ []byte, more bool) ([]byte, error) {
 	if more {
 		// We've already sent everything.
 		return nil, errors.New("unexpected server challenge")

smtp/example_test.go

@@ -3,7 +3,7 @@
 //
 // Original net/smtp code from the Go stdlib by the Go Authors.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the [PROJECT ROOT]/LICENSES directory.
+// LICENSE file that can be found in this directory.
 //
 // go-mail specific modifications by the go-mail Authors.
 // Licensed under the MIT License.

smtp/smtp.go

@@ -3,7 +3,7 @@
 //
 // Original net/smtp code from the Go stdlib by the Go Authors.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the [PROJECT ROOT]/LICENSES directory.
+// LICENSE file that can be found in this directory.
 //
 // go-mail specific modifications by the go-mail Authors.
 // Licensed under the MIT License.

smtp/smtp_test.go

@@ -3,7 +3,7 @@
 //
 // Original net/smtp code from the Go stdlib by the Go Authors.
 // Use of this source code is governed by a BSD-style
-// license that can be found in the [PROJECT ROOT]/LICENSES directory.
+// LICENSE file that can be found in this directory.
 //
 // go-mail specific modifications by the go-mail Authors.
 // Licensed under the MIT License.