DMARC is used to protect your email from email spoofing. DMARC use SPF and DKIM record to validate your email. DMARC is a TXT record added in your domain DNS. DMARC record look like

p=POLICY_HERE This specifies what to do with incoming email that fails DMARC. Valid options are none, quarantine and reject. p=none […]

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Postfix disable IPv6

To disable IPv6 on postfix mail server, edit


Replace with

Restart postfix

Method 2


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Configure postfix to relay mails using Gmail

Install postfix

Create file


Save and exit editor. Run

Edit postfix configuration file

Find and remove

At end of the file, add

Restart postfix

Now all mails will be forwarded using gmail. Test Email Delivery Install mailutils

On CentOS

To sent test email, run […]

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Zimbra Unable to validate certificate chain


On installing SSL on Zimbra mail server, i get following error

This was due to SSL cert chain. The ca-bundle file they provided did not work with Zimbra. This is due to some issue with the order in witch CA Certificate files are placed. Here is zimba documentaion related to this issue I […]

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PowerMTA is highly configurable mail server for email marketing. Unlike general email servers, PowerMTA can be configured to meet your special mail delivery requirements. Install PowerMTA Create SMTP user in PowerMTA Change SMTP port in PowerMTA Create DKIM in PowerMTA PowerMTA allow an IP to sent email Enable Web Monitor UI in PowerMTA PowerMTA route […]

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Install Open Source Zimbra Mail Server

To install Zimbra, Download latest version form At the time of this post, latest version is 8.8.8 GA Release. System Requirments Zimbra recommends 8 GB of RAM. For detailed system requirements, see Zimbra System Requirements I have installed on servers with 4 GB RAM with out any problem. If you are installing on server […]

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