mail() does not work out of the box

[coconitro]

It seems that the sendmail_from config setting isn't right? If additional configuration is required for this to work should this be noted in the documentation?

When running php -i | grep sendmail_path I get this

php -i | grep sendmail_path
sendmail_path =>  -t -i  =>  -t -i 

When running this script

<?php 
mail('test@example.com', 'Subject', 'Body');
?>

The results are this:

sh: 1: -t: not found

[md5]

The docs say this:

Where the sendmail program can be found, usually /usr/sbin/sendmail or /usr/lib/sendmail. configure does an honest attempt of locating this one for you and set a default, but if it fails, you can set it here.

Looks like configure is failing to set a value for sendmail_path since there is no sendmail binary installed when PHP is built.

[coconitro]

I ended up trying to add sendmail or postfix to a container extending from php:5.6-apache and pointing the php.ini sendmail_path to them correctly but ran into the problem of multiple services running inside the container.

Ended up settling on using ssmtp to solve this. Here is a Dockerfile that should work with mail() out of the box.

FROM php:5.6-apache

RUN apt-get update && \
  apt-get install -y ssmtp && \
  apt-get clean && \
  echo "FromLineOverride=YES" >> /etc/ssmtp/ssmtp.conf && \
  echo 'sendmail_path = "/usr/sbin/ssmtp -t"' > /usr/local/etc/php/conf.d/mail.ini

mail() should work out of the box with this container. I'm not sure if this is something that should be modified and changed in the base php container or documented somewhere. Thoughts?

[md5]

I don't think it's possible to have a reasonable default configuration for mail(). In the case of ssmtp, you need to point it at an SMTP server (likely providing credentials). Trying to use an actual MTA like Postfix or Sendmail means that multiple services will be running in the container, as you mention.

Given that, I think that documenting the issue and possible ways to fix it is the best that can be done.

I previously opened an issue for the wordpress image where users have mentioned other configurations they've used to get mail() working: docker-library/wordpress#30

[coconitro]

Good points. Seems the most Docker-like way to do this would be to have two containers, the php one and a MTA one, have ssmtp setup in the php one linked to the MTA one. Not the easiest thing in the world to document in a general manner. I'll close this for now since it doesn't seem like there are any actions that can be taken. Thanks for the insight.

[md5]

This PHP feature request is relevant (enable direct SMTP support on non-Windows systems), though it doesn't seem like they'll ever implement it: https://bugs.php.net/bug.php?id=29629

[stuartz-VernonCo]

It took me way too much time to research and empliment. Hope this helps someone else.

for simple solution that may be filtered by spam filters:
for more details, information used from: [http://www.tothenew.com/blog/setting-up-sendmail-inside-your-docker-container/]

Dockerfile bare-bones example:
FROM php:apache
'#' debian:jessie, apache on port 80, php:latest
'#' retrieve needed system programs
RUN apt-get update && apt-get upgrade -y sendmail && rm -rf /var/lib/apt/lists/*
COPY ./app/ /var/www/html/
'#' to be ran with docker exec later
COPY ./config_files/mail_config.sh /var/www'
'#' php:apache recommends using your own php.ini
COPY ./config_files/php.ini /usr/local/etc/php/php.ini

.config_files/mail_config.sh example:
line=$(head -n 1 /etc/hosts)
line2=$(echo $line | awk '{print $2}')
echo "$line $line2.localdomain" >> /etc/hosts
/etc/init.d/sendmail start
sleep 1
service apache2 graceful

add to your ./config_files/php.ini:
sendmail_path = /usr/sbin/sendmail -t -i

Then run the following to initiate it after starting container
or put as a CMD in Dockerfile if yours doesn't already have a CMD.
docker exec container_name bash /var/www/mail_config.sh

EDIT May 16, 2019

added ability to send as desired domain (see replace MASQUERADE_AS)

previous EDIT Feb 10,2017

I had another program that was editing the /etc/hosts file at start up, and so I changed my mail_config.sh The change also made it possible to not have to edit /etc/mail/sendmail.mc to remove localhost access thanks to a hint from @charafsalmi.

** /mail_config.sh

#!/bin/sh
#add host to /etc/hosts
host=$(hostname)
line=$(cat /etc/hosts |grep [1]27.0.0.1)
#placed at end to prevent being changed by weave
echo "$line noreply@yourdomain.com $host" >> /etc/hosts

#or if file is not being changed by other applications
#sed -i -e "s/$line/$line noreply@yourdomain.com $host/g" /etc/hosts

#finally
echo "$host" >> /etc/mail/relay-domains
replace MASQUERADE_AS with your domain to have it send mail out as the desired domain
line=$(cat /etc/mail/sendmail.mc | grep [M]ASQUERADE_AS)
's/^"$line".*/MASQUERADE_AS(`YOURDOMAIN.COM')dnl/' /etc/mail/sendmail.mc
m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
#start service
service sendmail restart # or sendmail -bd

[charafsalmi]

@stuartz-VernonCo do you know wether there is anything more to do to get it working with docker php-fpm or not ?

Everytime I send a mail I get a 504 error.

[stuartz-VernonCo]

@charafsalmi Time out waiting for a response (504) could be an issue with firewall not allowing the connection back in, or on AWS not allowing emails to be sent out on port 25 to prevent spam. Could be a number of things. On AWS, I used a queue on a database for applications sending out email, and smtp the emails through our office365.
Have you tried the container inside your LAN to send to a local email? Remove the network obstacles and if it works, focus on the network rules that are keeping it from working else where.

[charafsalmi]

@stuartz-VernonCo thank you !

it took me wayyyy so much time to find out why it wasn't working… it was not about the firewall, it was about what sendmail is expecting us to put in /etc/hosts

The last line of /etc/hosts has to contain this structure : [IP] "your.domain.com" [HOSTNAME]

So, once I changed my /etc/hosts to 127.0.0.1 noreply.domain.com e0dd810b0efd and restarted docker, it worked.

It's sad that sendmail doesn't give any clue about this.

# echo "127.0.0.1 noreply.domain.com $(hostname)" >> /etc/hosts