Using curl to send email - linux

Question

How can I use the curl command line program to send an email from a gmail account?
I have tried the following:
curl -n --ssl-reqd --mail-from "<sender#gmail.com>" --mail-rcpt "<receiver#server.tld>" --url smtps://smtp.gmail.com:465 -T file.txt
With file.txt being the email's contents, however, when I run this command I get the following error:
curl: (67) Access denied: 530
Is it possible to send an email from an account that is hosted by a personal server, still using curl? Does that make the authentication process easier?

Answer 1

curl --ssl-reqd \
--url 'smtps://smtp.gmail.com:465' \
--user 'username#gmail.com:password' \
--mail-from 'username#gmail.com' \
--mail-rcpt 'john#example.com' \
--upload-file mail.txt
mail.txt file contents:
From: "User Name" <username#gmail.com>
To: "John Smith" <john#example.com>
Subject: This is a test
Hi John,
I’m sending this mail with curl thru my gmail account.
Bye!
Additional info:
I’m using curl version 7.21.6 with SSL support.
You don't need to use the --insecure switch, which prevents curl from performing SSL connection verification. See this online resource for further details.
It’s considered a bad security practice to pass account credentials thru
command line arguments. Use --netrc-file. See the documentation.
You must turn on access for less secure apps or the newer App passwords.

Answer 2

if one wants to send mails as carbon copy or blind carbon copy:
curl --url 'smtps://smtp.gmail.com:465' --ssl-reqd \
--mail-from 'username#gmail.com' --mail-rcpt 'john#example.com' \
--mail-rcpt 'mary#gmail.com' --mail-rcpt 'eli#example.com' \
--upload-file mail.txt --user 'username#gmail.com:password' --insecure
From: "User Name" <username#gmail.com>
To: "John Smith" <john#example.com>
Cc: "Mary Smith" <mary#example.com>
Subject: This is a test
a BCC recipient eli is not specified in the data, just in the RCPT list.

Answer 3

Crate a simple email.conf file like so
Username: hi#example.com
Password: OKbNGRcjiV
POP/IMAP Server: mail.example.com
And simply run sendmail.sh, like so after making it executable (sudo chmod +x sendmail.sh)
./sendmail.sh
Code
#!/bin/bash
ARGS=$(xargs echo $(perl -anle 's/^[^:]+//g && s/:\s+//g && print' email.conf) < /dev/null)
set -- $ARGS "$#";
declare -A email;
email['user']=$1
email['pass']=$2
email['smtp']=$3
email['port']='587';
email['rcpt']='your-email-address#gmail.com';
email_content='From: "The title" <'"${email['user']}"'>
To: "Gmail" <'"${email['rcpt']}"'>
Subject: from '"${email['user']}"' to Gmail
Date: '"$(date)"'
Hi Gmail,
'"${email['user']}"' is sending email to you and it should work.
Regards
';
echo "$email_content" | curl -s \
--url "smtp://${email['smtp']}:${email['port']}" \
--user "${email['user']}:${email['pass']}" \
--mail-from "${email['user']}" \
--mail-rcpt "${email['rcpt']}" \
--upload-file - # email.txt
if [[ $? == 0 ]]; then
echo;
echo 'okay';
else
echo "curl error code $?";
man curl | grep "^ \+$? \+"
fi
more

Answer 4

Mind that the form of mail.txt seems to be important / CRLF for win, LF for Linux, special characters etc.
Finally after struggling 2 hours, it works for me for GMX (they tell their SMPT port to be 587 - and further down in small letters the hint: "also 465 can be used with SSL"):
UNDER Linux (TinyCore Linux on Raspberry 3B+ with curl.tcz installed):
curl --ssl-reqd --url 'smtps://mail.gmx.net:465' --user 'mymail#gmx.at:mymailPassword' --mail-from 'mymail#gmx.at' --mail-rcpt 'mymail#gmx.at' --upload-file mail.txt
UNDER Windows:
curl --ssl-reqd --url "smtps://mail.gmx.net:465" --user "mymail#gmx.at:mymailPassword" --mail-from "mymail#gmx.at" --mail-rcpt "mymail#gmx.at" --upload-file mail_win.txt
with mail.txt:
From: "User Name" <mymail#gmx.at>
To: "John Smith" <mymail#gmx.at>
Subject: This is a test
Hi John,
Im sending this mail with curl thru my gmx account.
Bye!

Answer 5

Note that if Perl's "system()" function is used to execute the curl command, each argument 'word' is a separate item in the argument array, and words must NOT be quoted.
Also note that if sending via Gmail after May 30, 2022, the gmail account must be set up with 2-factor authentication and then you must create an "App Password". The App Password is a long character string that acts as an alternative password and replaces the usual password on the "--user" parameter.