Holbihost: Anti-Spam Best Practice

Outgoing Anti-Spam Protection

This article contains the best practices for outgoing email from your server to the Internet. These practices must be followed so that your emails do not get filtered, blocked, or marked as spam on the Data-center level or other anti-spam organisations.

Why Holbihost does apply protective measures to outgoing emails?

For every IP available with Holbihost products and services we appear as the IP abuse contact for litigation in the WHOIS database. If an IP is reported to organisations such as Spamhaus and SpamCop, which work to combat spam, malicious websites and phishing, then the reputation of the entire Holbihost network is at stake.

It is therefore important that Holbihost takes care of the reputation, quality and security of the network, which also forms an important part of your service.

How does protection system works?

Anti-spam system on the Data-center level is based on Vade Secure anti-spam technology.

What to do after receiving IP Block email alert

Important steps to take on receiving a block alert BEFORE the affected IP can be unblocked.

  • stop sending email (e.g. stop all mail software such as qmail, Postfix, Sendmail etc.)
  • check the email queue (e.g. qmHandle for qmail, postqueue -p for Postfix)
  • analyse your logs using the Message-ID found in the block alert

Can I get whitelisted?

It is not possible to get a whitelisting, i.e. a filtering exclusion on the outgoing emails from your server.
We can only assist you with the logs diagnosis, if the Message-IDs are unknown and not part of your legitimate emails or mailing lists.

False Positives

If you have checked and found that Message-ID are from your legitimate email, you should then ensure that your email messages comply with the RFC and the Best Practices indicated below. If they do comply, you can inform us by sending a sample of your email (including header). Our technical support team will then assist you with the next steps. Simply contact us via the email support interface in your hosting account.

RFC and Best Practices

RFCs (Request For Comments) are documents intended to describe technical aspects of the internet. They are produced and published by the IETF (Internet Engineering Task Force), a group which basically produces and defines standards.
For more information, see: RFC, IETF and Internet Draft

Best practices are recommended methods which are often based on these documents and are intended to advise you on the best way to proceed. In this instance, this means the basic rules to follow so that your emails are not marked as spam.

Sending Volume

If your outgoing email volume is very high, you are advised to:

  • reserve (order) an IP block dedicated solely to email usage
  • request reverses on all IPs

This operation will enable you to simultaneously isolate the IP and domain reputation if you send emails for various domains, to receive the complaints, and thus do what is necessary to get unblocked by various organisations. It also enables you to locate a problem more quickly on a form that uses domain X or Y, as the emails are not sent out from the same IP and don’t have the same reverse.

Email content

Avoid using spammer keywords in your emails such as “buy” and “last chance”, and avoid capital letters, impersonal subjects, exclamation marks, and % discounts.

Don’t forgot to provide an unsubscribe link for people who have not requested to receive your email or who believe it to be illegitimate.

Be particularly careful to ensure that your emails contain the sender’s address (or an alias), a subject, and a correct ratio of text, images and links in the body of the message.
The text vs. image and text vs. link ratio must be high. Don’t overload the email with hypertext links and avoid Javascript.

FBL – Feedback Loop

This system will enable you to follow up on feedback provided by some internet service providers directly, informing you that their users have marked your message as illicit, and that it has thus been classified as spam. This will enable you to interact with these ISPs directly concerning your reputation. Some FBLs:

  • Yahoo
  • AOL Postmaster
  • SpamCop
  • Outlook & live.com

Authentication

Some authentication services enable you to protect your reputation.

Sender-ID
An email authentication technology developed by Microsoft which validates the authenticity of your domain name by verifying the IP address of the sender. This technology is based on the IETF standard: RFC4406

SPF
Sender Policy Framework is a standard for verififying the domain of the sender. It is based on RFC4408 and consists of adding an SPF or TXT field to the domain DNS, which contains the list of IPs authorised to send emails from this domain.

Reverse DNS
Reverse enables your IP to be “translated” into your domain. That allows the domain associated with the IP address to be found.

DKIM
DKIM This standard is described in RFC4871.
AOL, Google (Gmail) work on this basis. Official website: DKIM

How to unblock?

IMPORTANT !!
Do not request unblock the IP under any circumstances without having suspended the sending of emails from your server, otherwise you will immediately get blocked for a second time (and a longer duration).

Send us request via Support System. Our team will review your ticket and take appropriate measures.

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