Use socat to emulate an SMTP mail SERVER

socat TCP4-LISTEN:25,fork EXEC:'bash -c \"echo 220;sleep 1;echo 250;sleep 1;echo 250;sleep 1;echo 250;sleep 1;echo 354;sleep 1;echo 250; timeout 5 cat >> /tmp/socat.log\"'

Lots of scripts show you how to use socat to send an email to an SMTP server; this command actually emulates an SMTP server! It assumes the client is only sending to one recipient, and it's not at all smart, but it'll capture the email into a log file and the client will stop retrying. I used this to diagnose what emails were being sent by cron and subsequently discarded, but you can use it for all sorts of things.

Sample Output

EHLO host.example.com
MAIL FROM:<root@example.com>
RCPT TO:<root@example.com>
DATA
Received: by host.example.com (Postfix, from userid 1234)
	id 955; Wed, 26 Nov 2014 12:56:03 -0800 (PST)
From: root@example.com (Cron Daemon)
To: root@example.com
Subject: Cron <root@example.com>    
Content-Type: text/plain; charset=UTF-8
Message-Id: <2014112.57348E5@host.example.com>
Date: Wed, 26 Nov 2014 12:56:01 -0800 (PST)

foobar: cannot remove user's mustache.
.
QUIT

By: pfudd

2014-11-26 21:14:05

cat echo sleep smtp socat Linux UNIX

Submit An Alternative

What Others Think

I found this extremely helpful, as it solves a problem I have with oldish hardware which cannot send email anymore due to modern restrictions (Auth,TLS,etc.), at the same time it made me aware of how primitive email transport really is. In my case the line as is didn't quite work, as it did not suffice to feed the client the response number, so the transfer was never terminated. The solution I am working with presently for an intelligent power-cord (NETIO-230B) follows. # socat TCP4-LISTEN:25,fork EXEC:'bash -c \"echo 220 welcome;sleep 1;echo 250 OK;sleep 1;echo 334 VXNlcm5hbWU6;sleep 1;echo 334 UGFzc3dvcmQ6;sleep 1;echo 235 2\.7\.0 Authentication successful;sleep 1;echo 250 OK;sleep 1;echo 250 OK;sleep 1;echo 354 Send;sleep 1;echo 250 OK;sleep 1;echo 221 BYE;timeout 5 cat >> /tmp/socat.log\"' The outlet has 4 watchdogs, which send email on failing devices. I can now either watch the file for alteration or extend the line to a small script that forwards the message to the real world email system. Some helpful advice is found here: "https://www.samlogic.net/articles/smtp-commands-reference.htm" and here "https://github.com/craSH/socat/blob/master/EXAMPLES" Thanks for the line, MulMic

MulMic · 179 weeks and 5 days ago

where to get shrooms dried mushrooms african pyramid mushroom african transkei mushroom albino penis envy b+ mushrooms blue meanies mushroom brazilian magic mushroom burmese mushroom golden teacher mushroom ko samui super strain malabar coast martinique mexican mushroom mushroom british columbia super thai mushroom nepalese chitwan mushroom penis envy texas penis envy 6 texas yellow caps vietnamese white jedi mind fuck tri coloured ecuadorian mushroom magic mushsroom edibles mexican cubensis psychedelic chocolate bar where to get shrooms dried mushrooms african pyramid mushroom african transkei mushroom albino penis envy b+ mushrooms blue meanies mushroom brazilian magic mushroom burmese mushroom golden teacher mushroom ko samui super strain malabar coast martinique mexican mushroom mushroom british columbia super thai mushroom nepalese chitwan mushroom penis envy texas penis envy 6 texas yellow caps vietnamese white jedi mind fuck tri coloured ecuadorian mushroom magic mushsroom edibles mexican cubensis psychedelic chocolate bar midnight mint psychedelic chocolate bar origin mango psilo gummies 0.25g-1g origin strawberry psilo gummies 0.25g-1g penis envy psychedelic chocolate bar psilocybin cube gummies vegan dark chocolate psychedelic chocolate bar microdoses brain capsules 50mg-200mg chill capsules 50mg-200mg clarity capsules 50mg-200mg health capsules 50mg-200mg love capsules 50mg-200mg mood capsules 50mg-200mg pure capsules 50mg-200mg social capsules 30 pack 350mg social capsules 5 pack 350mg buy weed online without medical card marijuana flowers types of concentrates cannabis cartridges buy edibles online legal marijuana shatter cannabis wax marijuana hash buy psychedelic online tinctures for anxiety cannabis seeds bank weed smoker accessories birthday cake kush acdc strain ace killer og strain ak 47 strain alaskan thunder fuck alien kush strain ambrosia kush strain atomik moon rocks cbd 40.57% atomik moon rocks diamond 58.77% banana og strain bc big bud strain birthday cake kush blue cheese strain blue dream og kush blue moonrock kush blue rhino strain blueberry kush strain bruce banner strain cannabis trim cherry pie strain cannatonic strain citrix strain dark star kush durban poison strain eleven roses strain g13 haze strain gelato strain girl scout cookies flavors girl scout cookies online granddad purple strain grape nana weed strains grape pie strain green crack strain guava kush strain hawaiian skunk jack herer strain mendo breath weed mighty mango mr nice guy weed blue mystic strain northern lights strain northern lights moon rock platinum og kush gas og strain pink og kush platinum hawaiian strain pootie tang strain purple mimosa strain purple white widow strain smart buds sour diesel weed strain sour moonrock strain space monkey tins strawberry banana weed sun rocks super citrus haze strain super silver haze wedding cake strain exotic white widows strain zombie kush strain all natural pistachio crunch apple fritter vape cartridge aura edibles gummy-candy banana og cartridge birthday cake dank vape pen cartridg biscotti vape cartridge blackberry kush cartridge bliss edibles 300mg thc blue dream cartridge 180mlg berry blue raspberry 500mg-chocolate chip- cookies atomic wheelchair activated thc distillate strike gold blue dream shatter bubba kush shatter cbd dried organic ginger blueberry kush vape cartridges chemdawg shatter 50mg choco chunk cookies cookies and cream vape delta 8 thc capsules do-si-dos cartridges durban poison vape cartridge eds and bills edible candy bags forbidden fruit cartridge fruity pebbles cartridge gelato cartridge 1000mg girl scout cookies shatter girl scout cookies wax gorilla glue #4 wax gorilla glue cartridge gorilla glue shatter grand daddy purple kush wax gsc cartridge hardcore og cartridge jack herer cartridge jack herer wax jet fuel cartridge juicy melon cartridge khalifa kush shatter kosher kush cartridge labanese camel hash lemon berry cartridge

johnson20007 · 53 weeks ago

https://seofox.ir/seo/ https://seofox.ir/gray-hat-seo/ https://seofox.ir/search-engine/ https://seofox.ir/page-rank/ https://seofox.ir/backlink-definition/ https://seofox.ir/seo-techniques/ https://seofox.ir/technical-seo/ https://seofox.ir/on-page-seo/ https://seofox.ir/seo-tools/ https://seofox.ir/off-page-seo/ https://seofox.ir/seo-consultation/ https://seofox.ir/on-page-seo/ https://seofox.ir/google-seo-book/ https://seofox.ir/add-site-in-google/ https://seofox.ir/category/seo/ https://seofox.ir/seo-training/ https://seofox.ir/order/ https://seofox.ir/page-speed/ https://seofox.ir/seo-company https://seofox.ir/white-hat-seo/ https://seofox.ir/seo-principles/ https://seofox.ir/category/seo-content/ https://seofox.ir/seo-checklist/ https://seofox.ir/category/seo-content/ https://seofox.ir/google-algorithms/ https://seofox.ir/google-penalty-removal/ https://seofox.ir/rules-of-link-building/ https://seofox.ir/analyze-seo/ https://seofox.ir/backlink/ https://seofox.ir/seo-services-prices/ ??? ? ????? ????

seofox · 52 weeks and 5 days ago

seofox · 51 weeks and 6 days ago

Amazing! This blog looks just like my old one! It's on a completely different subject but it has pretty much the same layout and design. Wonderful choice of colors! Pug Puppies for Sale Near Me PUG PUPPY FOR SALE NEAR ME PUG PUPPIES FOR SALE pug puppies for sale in kentucky Pug Puppies for Sale Under $500 Near Me pug puppies for sale in texas pugs puppies for sale teacup pugs for sale pug puppies for sale by owner pug puppies ohio

rahimhh21 · 24 weeks and 3 days ago

AnthonyLewis9201 · 18 weeks and 4 days ago

Perfecthomepugs · 14 weeks and 5 days ago

Princesmith · 8 weeks ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

You must be signed in to comment.

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands

Similar Commands

mailx to send mails from console

Display email addresses that have been sent to by a postfix server since the last mail log rollover

SMTP Analysis

Connect to SMTP server using STARTTLS

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for:

» all commands
» commands with 3 up-votes (commandlinefu3)
» commands with 10 up-votes (commandlinefu10)