This library is an evolution from the mmcomm project, applying some things I learned there to a library that can be easily extended by including in other projects that will send and track emails sent through an already-setup SMTP session.

The share library depends on two other libraries, OpenSSL and my own code64. The mailer command additionally uses my readini project to read a configuration file.

Install OpenSSL like this:

sudo apt-get install libssl-dev

My libraries should be cloned, built, and installed from my GitHub account:

clone https://www.github.com/cjungmann/code64
clone https://www.github.com/cjungmann/readini

cd code64
make
sudo make install

cd ../readini
make
sudo make install

I am learning a lot about SMTP and POP3 mail protocols. Many of the references I have used are recorded here

This small program uses the libmailcb library to send emails from the command line. It writes its output to stdout, and can be configured to read from stdin to make the command more than just an example program.

While most of the settings like host, port, from, etc, can be explictly set on the command line, it is much more convenient to have a configuration file from which the settings can be read at run time.

By default and for now, in the absence of a specific -c config_file_name command line option, mailer will try to read configuration information from ./mailer.conf.

The configuration file consists of sections labelled with a word or phrase in square brackets, followed by settings lines where the text up to the first space is the tag, and what follows the spaces between the tag and the rest of the text is the tag's value.

For example, host smtp.gmail.com will have a tag of host and a value of smtp.gamil.clom. The intervening spaces will be trimmed off, as well as any trailing spaces, not to mention comments.

Here is a sample mailer.conf file:

[defaults]
logfile         ./mailer.log   # file to which, instead of stderr, log messages should be written.
default-account gmail          # account to use if no other account is specified


[gmail]
host     smtp.gmail.com
port     587
use_tls  on                    # Start TLS after HELO
user     [email protected]  # for the RCV FROM: of the email envelope
from     [email protected]  # for email header.  This may disappear
password abcdefghijklmnop      # Google-provided password to authorize two-factor authentication.

[gmail pop]
host     pop.gmail.com
type     pop                   # flag to initiate POP processing
port     995
use_tls  on
user     [email protected]
password abcdefghijklmnop