Get Around Linode Blocking SMTP

/ Computer / Linux, WordPress

You need an internet host without SMTP blocked like your home internet service. The idea is to use it as a relay on a different port like 225 which isn’t blocked.

Setup your localhost to deliver your email.

Steps:

 Step 1: Get a Gmail id and password

 Step 2: Login in and switch to root using: sudo su -

 Step 3: Run the below commands (assuming debian packages like ubuntu):
	apt-get update
        apt-get install sendmail sasl2-bin mailutils

 Step 4: Create an authentication file
        cd /etc/mail
	mkdir -m 700 authinfo
	cd authinfo/
	emacs (or vi or vim or nano, etc) gmail
        add the below content to the file:

	AuthInfo: "U:root" "I:your-gmail-id@gmail.com" "P:your-password"

        Edit using your gmail id and password

Step 5: Create a hash map of the file:
	makemap hash gmail < gmail

Step 6: Go to /etc/mail and open sendmail.mc
       Add the following lines to sendmail.mc file right above MAILER_DEFINITIONS:
	#GMail settings:
	define(`SMART_HOST',`[smtp.gmail.com]')dnl
	define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
	define(`ESMTP_MAILER_ARGS', `TCP $h 587')dnl
	define(`confAUTH_OPTIONS', `A p')dnl
	TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
	define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
	FEATURE(`authinfo',`hash -o /etc/mail/authinfo/gmail.db')dnl


Step 7: Run the two commands from /etc/mail
	make
	/etc/init.d/sendmail reload

Step 8: Now open https://www.google.com/settings/security/lesssecureapps
       and Allow less secure apps: ON

Step 9: Verify a test mail using
	echo "Test" | mail -s "This is a test" some-id@some-domain.com

Setup a port forwarding on your router. I used port 225 on the outside to port 25 on the internal machine running sendmail.

Next edit /etc/mail/sendmail.mc and change:

< DAEMON_OPTIONS(`Family=inet, Name=MTA-v4, Port=smtp, Addr=127.0.0.1')dnl
> DAEMON_OPTIONS(`Family=inet, Name=MTA-v4, Port=smtp')dnl

removing the , Addr=127.0.0.1

This will open up port 25 on your sendmail server.

We’re still not done yet because relaying is not allowed. Add a file named /etc/mail/relay-domains. The contents of the file should contain every domain, one per line of each domain that you want to relay.

In /etc/mail as root re-run the following commands:
	make
	/etc/init.d/sendmail reload

Now from your Linode-hosted domain, you may connect to your sendmail server on the outside port, unauthenticated and it will be relayed onto the gmail servers authenticated.

Update:

If you are using WordPress follow this guide:

https://wpmailsmtp.com/docs/how-to-set-up-the-gmail-mailer-in-wp-mail-smtp/?utm_source=WordPress&utm_medium=setup-wizard&utm_campaign=liteplugin&utm_content=Read%20how%20to%20set%20up%20the%20Gmail%20mailer#create-app