Clients are unable to receive my emails

Question

I am getting following message after sending email to my client's official email address:

Subject: Delivery Status Notification (Delay)

This is an automatically generated Delivery Status Notification

THIS IS A WARNING MESSAGE ONLY.

YOU DO NOT NEED TO RESEND YOUR MESSAGE.

Delivery to the following recipient has been delayed:

     [e-mail]

Message will be retried for 2 more day(s)

Technical details of temporary failure: 
Google tried to deliver your message, but it was rejected by the server for the recipient domain kentech.ie by mx.kentech.ie. [91.103.2.154].

The error that the other server returned was:

554-Service unavailable; Client host [mail-pf0-f169.google.com] blocked using 554-Barracuda Reputation;
554 http://www.barracudanetworks.com/reputation/?r=1&ip=182.69.185.110

Its happening very frequently.

Any help will be very much appreciated.

Answer 1

Its happening very frequently.

From the page you linked to:

Sorry, your email was blocked

We are sorry you have reached this page because an email was blocked based on its originating IP address having a "poor" reputation. The "poor" reputation may have been caused by one of the following reasons:

• Your email server contains a virus and has been sending out spam.
• Your email server may be misconfigured.
• Your PC may be infected with a virus or botnet software program.
• Someone in your organization may have a PC infected with a virus or botnet program.
• You may be utilizing a dynamic IP address which was previously utilized by a known spammer.
• Your marketing department may be sending out bulk emails that do not comply with the CAN-SPAM Act.
• You may have an insecure wireless network which is allowing unknown users to use your network to send spam.
• In some rare cases, your recipient's Barracuda Spam Firewall may be misconfigured.

That page also contains a "Look IP Reputation" button.

Click on it and you will get:

The IP address 182.69.185.110 is listed as "poor" on the Barracuda Reputation System. To request removal, please click here.