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Four Deliverability Insights To Avoid Being Flagged As Bulk Email

(This post originally appeared on

After you have uncovered that you may have some “bulking” going on (i.e. your emails are ending up in the bulk folder), you will need to get a rough understanding as to what the underlying causes might be before being able to put a corrective action in place.

Here are the some of the main things to look at:

IP / Sending Domain Reputations

Reputation of your sending IPs or sending domains play a huge part in the decisions behind spam filtering technology. Often impacted heavily by engagement, these filters tend to be the most common stumbling block with senders experiencing spam/bulking issues. Separating your mail streams by subdomains and various IP pools will help you monitor and track variations in reputations between them.

This is also a great way to keep things like transactional mail for password resets or new account registrations isolated from possible bulking issues.

Example tools for looking up IP and sending domain reputations include:, &

Message Construction / HeadersBulletProofEmail_250

Ensure that the headers within your email are correct as incomplete or incorrect headers can cause red flags. Additionally, incorrectly formatted multi-part messages or content encoding issues will cause ISPs to give up on trying to deliver your mail to the end recipient.

Take your time to correctly format, style and encode your messages to best deliver your mail.

Example tools for testing message construction and headers: &

URLs within the email

The links / URLs within your email can also be causing the bulking.

Example tools for looking up URL reputation: &

Testing is key

While using some of the example sites that listed above is a good place to start, these should not be taken as the absolute truth. Testing with known variations that you know will go to the inbox may help you isolate those items with the most impact. Often, you will see that you can get it down to just a single element that is causing the bulking.

Based on those results, you will have a good idea of what changes you will need to make to get back in the inbox!

Other areas you like to test?  Reach me via email or Twitter.

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Whois: Mike Veilleux

Mike Veilleux is a Director of Product Management at Oracle Dyn Global Business Unit, a pioneer in managed DNS and a leader in cloud-based infrastructure that connects users with digital content and experiences across a global internet.