Issue
My goal is to send an email using curl with an html body with embedded image such as :
I'm sending the email like this :
curl "smtp://smtp.gmail.com:587" -v \
--mail-from "[email protected]" \
--mail-rcpt "[email protected]" \
--ssl -u [email protected]:secretpassword \
-T "message.txt" -k --anyauth
My message.txt looks like :
From: Some Name <[email protected]>
To: Some Name <[email protected]>
Subject: example of mail
Reply-To: Some Name <[email protected]>
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
The html decoded is :
<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>
How can I embed admin.png in this html and attach another file log.txt
to this email using curl and bash ?
Solution
The solution I came up with is to base64 encode all the attachment (image and text file) and to include them into the uploaded file directly in the multipart/mixed body such as :
--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--
The Content-Id header is used to identify the resource that can be referenced in the html with : cid: like :
<img src="cid:admin.png" width="150" height="50">
Here is a complete bash example to send an html email with and admin.png embedded image and a log.txt attached to it :
#!/bin/bash
rtmp_url="smtp://smtp.gmail.com:587"
rtmp_from="[email protected]"
rtmp_to="[email protected]"
rtmp_credentials="[email protected]: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
Answered By - Bertrand Martel