Question

我的目标是使用curl发送一封带有嵌入式图片的html正文的电子邮件，例如：

我发送这样的电子邮件：

curl "smtp://smtp.gmail.com:587" -v \
     --mail-from "sender@gmail.com" \
     --mail-rcpt "receiver@gmail.com" \
     --ssl -u sender@gmail.com:secretpassword \
     -T "message.txt" -k --anyauth

我的message.txt看起来像是：

From: Some Name <sender@gmail.com>
To: Some Name <receiver@gmail.com>
Subject: example of mail
Reply-To: Some Name <sender@gmail.com>
Cc: 
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="MULTIPART-MIXED-BOUNDARY"

--MULTIPART-MIXED-BOUNDARY
Content-Type: multipart/alternative; boundary="MULTIPART-ALTERNATIVE-BOUNDARY"

--MULTIPART-ALTERNATIVE-BOUNDARY
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: base64
Content-Disposition: inline

PGh0bWw+Cjxib2R5PgogICAgPGRpdj4KICAgICAgICA8cD5IZWxsbywgPC9wPgogICAgICAgIDxw
PlBsZWFzZSBzZWUgdGhlIGxvZyBmaWxlIGF0dGFjaGVkPC9wPgogICAgICAgIDxwPkFkbWluIFRl
YW08L3A+CiAgICAgICAgPGltZyBzcmM9ImFkbWluLnBuZyIgd2lkdGg9IjE1MCIgaGVpZ2h0PSI1
MCI+CiAgICA8L2Rpdj4KPC9ib2R5Pgo8L2h0bWw+Cg==
--MULTIPART-ALTERNATIVE-BOUNDARY--
--MULTIPART-MIXED-BOUNDARY

解码的html是：

<html>
<body>
    <div>
        <p>Hello, </p>
        <p>Please see the log file attached</p>
        <p>Admin Team</p>
        <img src="admin.png" width="150" height="50">
    </div>
</body>
</html>

如何在此html中嵌入admin.png并附加其他文件log.txt 使用curl和bash

发送到此电子邮件

Answer 1

我提出的解决方案是对所有附件（图像和文本文件）进行base64编码，并将它们直接包含在multipart/mixed主体中的上传文件中，例如：

--MULTIPART-MIXED-BOUNDARY
Content-Type: image/png
Content-Transfer-Encoding: base64
Content-Disposition: inline
Content-Id: <admin.png>
iVBORw0KGgoAAAANSUhEUgAAAIAAAACgCAIAAABL8POqAAAACXBIWXMAAAsTAAALEwEAmpwYAAAA
B3RJTUUH4AQNDwEVouBdqAAAG2xJREFUeNrtfX9oHFe25jdDBU5BG25BG7pABhXEkDJjSIsYIs1m
WbfJA8ubhcjjgdiTQNJOYCInj0RKYGIl8CbyPF4iZSCxEkgsB5LIgWQlL2Pcfow3bdgw0mMzox6e
....


--MULTIPART-MIXED-BOUNDARY
Content-Type: text/plain
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename=log.txt
c29tZSBsb2cgaW4gYSB0eHQgZmlsZSB0byBhdHRhY2ggdG8gdGhlIG1haWwK


--MULTIPART-MIXED-BOUNDARY--

Content-Id标头用于标识可在html中引用的资源：cid:，如：

<img src="cid:admin.png" width="150" height="50">

以下是一个完整的bash示例，用于发送带有admin.png嵌入图片和附加log.txt的html电子邮件：

#!/bin/bash

rtmp_url="smtp://smtp.gmail.com:587"
rtmp_from="sender@gmail.com"
rtmp_to="receiver@gmail.com"
rtmp_credentials="sender@gmail.com:secretpassword"

file_upload="data.txt"

# html message to send
echo "<html>
<body>
    <div>
        <p>Hello, </p>
        <p>Please see the log file attached</p>
        <p>Admin Team</p>
        <img src=\"cid:admin.png\" width=\"150\" height=\"50\">
    </div>
</body>
</html>" > message.html

# log.txt file to attached to the mail
echo "some log in a txt file to attach to the mail" > log.txt

mail_from="Some Name <$rtmp_from>"
mail_to="Some Name <$rtmp_to>"
mail_subject="example of mail"
mail_reply_to="Some Name <$rtmp_from>"
mail_cc=""

# add an image to data.txt : 
# $1 : type (ex : image/png)
# $2 : image content id filename (match the cid:filename.png in html document)
# $3 : image content base64 encoded
# $4 : filename for the attached file if content id filename empty
function add_file {
    echo "--MULTIPART-MIXED-BOUNDARY
Content-Type: $1
Content-Transfer-Encoding: base64" >> "$file_upload"

    if [ ! -z "$2" ]; then
        echo "Content-Disposition: inline
Content-Id: <$2>" >> "$file_upload"
    else
        echo "Content-Disposition: attachment; filename=$4" >> "$file_upload"
    fi
    echo "$3

" >> "$file_upload"
}

message_base64=$(cat message.html | base64)

echo "From: $mail_from
To: $mail_to
Subject: $mail_subject
Reply-To: $mail_reply_to
Cc: $mail_cc
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=\"MULTIPART-MIXED-BOUNDARY\"

--MULTIPART-MIXED-BOUNDARY
Content-Type: multipart/alternative; boundary=\"MULTIPART-ALTERNATIVE-BOUNDARY\"

--MULTIPART-ALTERNATIVE-BOUNDARY
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: base64
Content-Disposition: inline

$message_base64
--MULTIPART-ALTERNATIVE-BOUNDARY--" > "$file_upload"

# add an image with corresponding content-id (here admin.png)
image_base64=$(curl -s "https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_116x41dp.png" | base64)
add_file "image/png" "admin.png" "$image_base64"

# add the log file
log_file=$(cat log.txt | base64)
add_file "text/plain" "" "$log_file" "log.txt"

# add another image 
#image_base64=$(curl -s "https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_116x41dp.png" | base64)
#add_file "image/png" "something.png" "$image_base64"

# end of uploaded file
echo "--MULTIPART-MIXED-BOUNDARY--" >> "$file_upload"

# send email
echo "sending ...."
curl -s "$rtmp_url" \
     --mail-from "$rtmp_from" \
     --mail-rcpt "$rtmp_to" \
     --ssl -u "$rtmp_credentials" \
     -T "$file_upload" -k --anyauth
res=$?
if test "$res" != "0"; then
   echo "sending failed with: $res"
else
    echo "OK"
fi

Answer 2

再加上一个，您的代码示例有点让人误解，实际上是行不通的。就像您说的那样，您只需要将每个部分包围在边界中，就您而言，定界符为：

“-MULTIPART-MIXED-BOUNDARY”。

尽管如此，它可以是任何其他用户定义的字符串。您正在嵌套多个边界类型，这不是必需的。 HTML内容不需要进行base64编码，但是可以进行编码。

在每个定界符之前和之后都需要一个空白行。

我建议看一下W3的论文和示例：https://www.w3.org/Protocols/rfc1341/7_2_Multipart.html

curl：发送带有嵌入式图像和附件的HTML电子邮件

2 个答案: