Understanding Deliverability and Blacklisting

Email deliverability is multi-faceted and can be complex. When having deliverability issues, the problem may not be apparent. One minor issue can cause problems down the line. This article will provide answers on the more common deliverability issues. Article Contents Sender Permissions Shared and Dedicated IP Addresses IP Warming Authentication Blacklists Testing Emails			Available with:
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Sender Permissions

Permission is the most important aspect of deliverability. Senders must have permission to email recipients. When reviewing permissions, review how leads were signed up, and how lists were acquired. To that end, SharpSpring advises to send to recipients who have expressly opted-in. SharpSpring does not permit senders to use purchased, rented, scraped, or stolen lists. Practicing proactive list management also helps maintain permission status.

Additionally, consider if the sender has a permission reminder. Permission reminders are short text blocks, often found at the bottom of the email, that clarifies to subscribers how they were signed up to receive the email.

Shared and Dedicated IP Addresses

All email, regardless of content or origination, is sent over an Internet protocol (IP) address. A collection of IP addresses are called pools. The type of IP address may impact deliverability. For marketing automation, shared and dedicated addresses are used: 

• Shared addresses are single IP addresses that are shared by multiple websites on a single server.
  
  
• Dedicated addresses are IP addresses that are tied to only one website.

Shared addresses can pose problems with deliverability, as all websites tied to the shared address may be impacted by blacklisting or other issues.  In turn, these issues can impact deliverability rates (and therefore reputation). With shared addresses, IP addresses or pools may be tied to another sender with terrible reputation. If those senders are added to a blacklist or are otherwise blocked, all members of the shared address or pool will suffer the same fate. Shared addresses remove individual agency from senders and place them at the mercy of others.

By contrast, dedicated addresses are tied directly to a website or domain. In this, the sender has full control over all sends over the dedicated address. This places full responsibility with the dedicated sender. Additionally, this isolation serves to protect senders from outside influences and consequences. Consider also that, in being tied to a single website, a dedicated address becomes another aspect of a sender's brand identity. This identity reinforcement can help to build trust with recipients when sending emails.

IP Warming

Deliverability may also hinge on whether or not an IP address has been properly warmed. IP warming is where senders gradually send more and more emails over an address or pool. 

Shared addresses need not worry about IP warming. Dedicated addresses, however, must warm the address so that IP address can support the full volume of mail.
 

Authentication

Authentication plays a significant role in email deliverability. Unauthenticated emails will not be accepted by most major email providers, such as Gmail. Ensuring emails are authenticated is especially important. There are several factors that impact authentication, and if senders cannot send emails—especially those who previously were able to successfully send—then determining authentication status is paramount. 

First and foremost, authentication requires the sender to have SPF and DKIM set up. SharpSpring is a firm believer in this. As of February 2018, all SharpSpring accounts that have not set up DKIM are set as limited from sending emails until DKIM is set up and configured. DKIM, as email authentication, broadcast to recipient Mail Transfer Agents (MTAs) that SharpSpring is permitted to send your mail, and to also aid deliverability.

Even if emails are authenticated, IP addresses or pools may be impacted by poor reputation. Shared IP pools are especially at risk, as one sender can make things difficult for all others sending from the pool. If reputations are poor enough, entire IP pools or domains may be blocked from sending emails. It is imperative that senders maintain good email reputation.

Blacklists

Additionally, links in the emails—or even the emails themselves—may be part of a blacklist. Blacklists are third-party data sources that inform receiving email servers whether the sender or the email content should be considered as spam. As a third-party, these data sources do not actually block email, but email servers may choose to accept or reject the recommendations from blacklists.

There are hundreds of blacklists in every range of sophistication. They can range from cutting-edge, enterprise-grade systems using artificial intelligence to hobbyist blacklists run as personal projects. Some blacklists provide data on suspicious Internet protocol (IP) ranges, whereas others list sending domains found in email headers. Others list domain names found in email content, such as clickable links.

Spam filters often implement several blacklists simultaneously to provide comprehensive data on all parts of an email. Filters often ignore other blacklists that are inaccurate, out-of-date, or idiosyncratic.

SharpSpring has a team dedicated to deterring blacklisting and the healing of its sending IPs, with its intent being for the good of all senders on the platform. To learn what you can do to help prevent the risk of a blacklisting, refer to Email Best Practices.

Testing Emails

It is important to test emails to see if these emails are unauthenticated, blacklisted or otherwise impacted. SharpSpring recommends using MxToolBox. MxToolBox checks to see if CNAME records are properly set up and configured, whether or not emails have blacklisted content, and the overall sending domain status. Testing can only serve to benefit your sends.