Linux web hosting and server support tips

Tag: email

How to block Outgoing Port 25 for all VPS/Containers of SolusVM

How to block Outgoing Port 25 for all VPS/Containers of SolusVM(Both OpenVZ/KVM)

Sometimes,when providing VPS service, it is necessary to block mailing service for VPS. Otherwise your IP ranges will be blocked by RBLs and other common mail providers like Gmail, Hotmail, AOL, etc. It is recommended to open ports by case by case for your customers, after establishing trust with your client.

Normally we block the port using the “OUTPUT” chain. However, SolusVM uses the chain “FORWARD” for routing traffic from containers/VPSs.

So by adding following rules, you can block all outgoing mails ports completely for all VPSs.

iptables -I FORWARD -d 0.0.0.0/0 -p tcp -m tcp --dport 25 -j DROP
iptables -I FORWARD -d 0.0.0.0/0 -p tcp -m tcp --dport 465 -j DROP
iptables -I FORWARD -d 0.0.0.0/0 -p tcp -m tcp --dport 587 -j DROP

Then save the iptables by running

service iptables save

Disable/suspend email service for one domain – cPanel

Disable/suspend email service for one domain

From version 56, cPanel provides API support to disable email service for domain or email accounts. Please note this limit cannot be override by the user from their cPanel. This can be very helpful if there is any spamming activity and you just want to disable the email service feature for the domain for the time being.

You can run the below commands through SSH console

To suspend email service for a the cPanel user “aacenyor”

whmapi1 suspend_outgoing_email user=aacenyor

For unsuspending the account, please run the below command:

whmapi1 unsuspend_outgoing_email user=aacenyor

If you are not comfortable with SSH, you can also call these through browser XML.

Example:

To suspend
https://hostname.example.com:2087/cpsess##########/xml-api/suspend_outgoing_email?api.version=1&user=aacenyor

where replace hostname.example.com with your hostname
replace cpsess########## with WHM session id.

To un suspend
https://hostname.example.com:2087/cpsess##########/xml-api/unsuspend_outgoing_email?api.version=1&user=aacenyor

For older versions cPanel, you may refer to this below forum from cPanel. There is a workaround

https://forums.cpanel.net/threads/how-do-i-block-one-domain-from-sending-email-from-my-server.223731/#post920912

Disable greylisting completely – iRedmail

iRedMail is:
1. A ZERO COST, fully fledged, full-featured mail server solution. All components are free and open source software
2. It support unlimited domains and email accounts.
2. SpamAssassin, ClamAV, SPF, DKIM, greylisting, whitelisting, blacklisting.
3. Stores mail accounts in your favourte backend: OpenLDAP, MySQL, MariaDB, PostgreSQL.
4. Supports major Linux distros

You know how difficult is to configure a fully fledged email service you have tried. iRedmail do this heavy part for you. I would recommend this piece of software to everyone. I used to configure email server manually using Postfix, Postfixadmin, MySQL, SpamAssassin, etc. Even though I have done this several times, it needs 2-3 hours for setup. But iRedmail can do all of this and MORE in few minutes, thus saves lot of time.

How to disable greylisting completely

Greylisting is a method of defending e-mail users against spam. A mail transfer agent (MTA) using greylisting will “temporarily reject” any email from a sender it does not recognize

To disable greylisting completely, please remove plugin name greylisting in iRedAPD config file
/opt/iredapd/settings.py, parameter plugins =:
plugins = […, ‘greylisting’, …]

Restarting iRedAPD service is required.

Reject outgoing Spam – iRedmail server

iRedMail is:
1. A ZERO COST, fully fledged, full-featured mail server solution. All components are free and open source software
2. It support unlimited domains and email accounts.
2. SpamAssassin, ClamAV, SPF, DKIM, greylisting, whitelisting, blacklisting.
3. Stores mail accounts in your favourte backend: OpenLDAP, MySQL, MariaDB, PostgreSQL.
4. Supports major Linux distros

You know how difficult is to configure a fully fledged email service you have tried. iRedmail do this heavy part for you. I would recommend this piece of software to everyone. I used to configure email server manually using Postfix, Postfixadmin, MySQL, SpamAssassin, etc. Even though I have done this several times, it needs 2-3 hours for setup. But iRedmail can do all of this and MORE in few minutes, thus saves lot of time.

Reject outgoing Spam

iRedmail comes with Amavis, Spamassasin and Clamd. By default iRedmail will not block Outgoing spam message. However you can tweak Amavis configurations to reject such mails.

/etc/amavisd/amavisd.conf

Add following to $policy_bank{‘ORIGINATING’}

final_virus_destiny => D_DISCARD,
final_banned_destiny => D_REJECT,
final_spam_destiny => D_REJECT,
final_bad_header_destiny => D_REJECT,

Then restart amavis /etc/init.d/amavisd restart

This will reject all outgoing spam mails above the score

Of course tweak the spam score accordingly.

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