fatal: open /etc/postfix/main.cf: Permission denied

On a CentOS server, when sending mail from PHP scripts, mail failed to work. On checking postfix log file (/var/log/maillog), i see following error.

To fix this, disable selinux

To permanantly disable SELinux, run


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Postfix email forward

postfix mail server

On an Ubuntu Server, i done following to setup email forwarding. Install postfix

Edit /etc/postfix/main.cf, add following


Create Virtual mailbox


Create alias file, used for mail forwarding


Wth above configuration, mail coming to [email protected]_HERE.com will get forwarded to [email protected] Email coming to [email protected]_HERE.com get delivered […]

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iredmail increase mail attachment size

Default mail attachment size in iredmail is 10 MB. To increase mail attachment size, login to server as user root, run following commands

Here 104857600 is 100 MB in bytes (100 * 1024 * 1024). Change this as required. Sending very large file using mail attachment is not recommended, it is better use file […]

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Zimbra webmail not working on port 80/443

On Zimbra mail server, webmail stopped working on Port 80/443. Admin interface worked properly on url https://hostname:7071/. There is no errors displayed under monitor tab of Zimbra Admin. To fix, run

After running this, netstat -lntp start showing nginx running on port 80 and 443


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Zimbra Mail Server CentOS firewall settings

On CentOS 7 server with firewalld running, used following command to open ports used by Zimbra Mail Server.

See Zimbra, firewall-cmd […]

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Zimbra redirect webmail http to https

After Zimbra mail server installed, webmail work on url https://SERVER-HOSTNAME-HERE/ If you access webmail with out HTTPS, it won’t work. To set HTTP to redirect to HTTPS, login to server as root, switch to user zimbra


Wait few minutes, HTTP link will redirect to HTTPS.

You need to wait few minutes […]

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Install SSL Certificate on Zimbra mail server

Zimbra SSL install

To install SSL certificate for Zimbra Mail Server, login to server, switch to user zimbra

Now create file commercial.key, paste your Private key.

In commercial.crt, paste your SSL certificate.

Create commercial_ca.crt with content of your ca-bundle file.

Verify SSL cerificate

If SSL verified sucessfully, you can install it with command […]

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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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