How to setup an email to SMS forwarding gateway address with Postfix

SMS is an important tool in the arsenal I use to fight my never-ending war with productivity-destroying distractions.

Colleagues, friends, mailing lists, foes, viagra peddlers and nigerian princes send me in aggregate about 300 pieces of of e-mail every day, most of it not really that important. All of this noise can eat up an enormous amount of my attention so when I really need to concentrate I'm pretty much forced to ignore e-mail altogether for sometimes weeks at a time.

By comparison I only receive less than 10 SMS messages a day on my phone. They're also much shorter so I can go over them much more quickly. Consequently, it's usually much easier to get my attention with an SMS than an e-mail so people who know me have learned to use SMS as an out-of-band high-priority communication channel.

OTOH, I realize sending an SMS when you're busy hacking away at your computer can be a bit of a bother. You have to get out your phone, and fiddle around with a crappy virtual keyboard, etc.

So to get the best of both worlds I setup a secret email address on my mail server that sends e-mails directly to my phone as SMS. This address I give out to anyone who really needs to get in touch with me even when I'm offline.

This is implemented as a configuration on my postfix mail server, which pipes any email sent to a particular secret alias through to the extract-body.py script, which extracts the body of the message, and then to a little script which sends the body of the message to clickatell, a company that provides a simple SMS sending API.

Let's take a look behind the scenes:

# grep sms /etc/postfix/aliases
sms.c2e1: "|/usr/local/bin/extract-body.py|/usr/local/bin/clickatell-sendmsg --stdin to=0541232123 --maxlen=140"

# cat /usr/local/bin/clickatell-sendmsg
#!/bin/sh

export CLICKATELL_USER=liraz
export CLICKATELL_PASSWORD=mypassword
export CLICKATELL_API_ID=1232123

exec $(dirname $0)/clickatell-sendmsg.py "$@"

I'm attaching the required scripts to the end of this post.

Notes:

  • Clickatell's HTTP/HTTPS API can be easily invoked via curl

  • clickatell-sendmsg.py is a 133 line python wrapper around curl

  • extract-body.py is a is a 11 line wrapper that extracts the message body from an email that postfix pipes through to these aliases.

    Also, if a PGP signature exists it will delete it.

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Comments

PB's picture

based on your article, I am thinking about adjusting your scripts in order to create "my own" SMS gateway with Clickatell HTTP API (or SMTP API)

for example, if I would have some-secret-alias@mydomain.com

and subject is mobile phone number "+1 555 222 333"

I would like that message (first 140 or 160 characters) are sent to the mobile number from subject line

could you help me with your advice, how to achieve this, or even how to this some more efficient way

like having "number: +1 555 222 333" as a first line in the message, etc.

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