Avoid SPAM Filters

Article author
Jayson Verdibello
  • Updated


Email Service Providers (ESPs) often have strict rules in place to protect their users from unwanted or undesirable email messages. These "SPAM Blockers" can result in your emails bouncing and never reaching your intended audience. The strategies below can help you improve the delivery rates for the emails you send through Apollo.

Let's (Not) Bounce

Please note, the tips and guidelines listed below are only best practices. They are not guaranteed to eliminate all bounces or instances of SPAM blocked emails. SPAM filtering is user-specific—if someone marks an email as spam, their email service provider's spam filtering will update itself to catch similar emails in the future. Two people can receive the same email and encounter different filtering behavior.

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Email Deliverability Best Practices

At a high level, there are 2 primary causes for email bounces and ESPs marking emails as SPAM:

  1. Domain Reputation
  2. Email Content and Formatting
Stop, in the Name of Accuracy!

If you are SPAM blocked by a contact that you email, it doesn't mean that the contact email address is not accurate. It means that the contact likely exists and your email was either automatically or manually marked as unfit or inappropriate for delivery.

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Domain Reputation

For a better chance of avoiding SPAM blocked emails, follow the steps below to configure your domain settings.

Set Up the SPF, DKIM, and DMARC for Your Sending Domains

Adjusting Attributes

Welcome-listing your domain improves your deliverability and ISP reputation. You should configure the following attributes of your domain to help raise your SPAM score.

Set Up SPF Records: An authorization method that specifies which email servers are allowed to send and receive emails on behalf of your organization.
Set Up DKIM Policies: An authentication method that uses cryptography to securely encrypt and decrypt emails sent to and from your organization. Also prevents in-transit altering of messages being sent or received.
Set Up DMARC Policies: An authentication method that specifies how to handle emails that don't pass SPF and/or DKIM checks. DMARC also generates reports to prevent email spoofing.

Dive Into Developer Guides

Follow the Google Developer guides below for further reading.
Publish an SPF record
Publish a DMARC policy
Authenticate Your Email With DKIM

Master of Your Domain (Providers)

The information you need to configure SPF, DMARC and DKIM is specifically related to your own domain and is not in any way related to Apollo. Apollo doesn't have email servers so all emails are sent directly from your email provider. Instructions to configure SPF, DMARC and DKIM vary by domain provider. You should contact your domain provider directly to obtain this information and receive any support that you need.

It's important to remember that SPAM blockers are common and it is normal and expected that your domain may be flagged for SPAM on occasion. If you have already configured SPF, DMARC and DKIM and your domains are flagged for SPAM, you can consider implementing the following options:

Set Up a New Domain

This domain should be different than the primary sending domain and you should only use it to send marketing emails. Additionally, this requires you to create new mailboxes from this domain and add and replace them in Apollo for each user profile. For more information about how to connect mailboxes to Apollo, see the "Link Your Mailbox to Apollo.io" article.

Set Up a New Tracking Domain

A tracking domain is a secondary (or sub) domain name related to your original domain that allows Apollo to redirect a tracking pixel added to emails to track opens, clicks, and unsubscribes.

Tracking pixels are normally flagged as SPAM. Tracking domains redirect the attention of the email from your main domain and will help with deliverability.

Click here and follow the instructions to set up a new tracking domain.

Tighten Up Tracking Domains

You can expect that your emails will get flagged as SPAM on occasion. In these cases, the Tracking Subdomain allows you to spin up a new one every time a server flags your domain as SPAM. Make sure you follow the same instructions to create a new tracking subdomain with a different name to reset your deliverability whenever needed.

Connect Apollo to a SendGrid Account

SendGrid is a mass emailing service that uses its own email servers. It also replaces the tracking URLs and directs them to SendGrid servers to resolve deliverability issues. If you connect your Apollo account to SendGrid, you do not need to configure a Tracking Subdomain because SendGrid manages your tracking links on their end. For additional information, please see the "SendGrid Integration Overview" article.

There Can Only Be One (Tracking Link)

If your emails are flagged as SPAM while your Apollo account is connected to SendGrid, it may be necessary for you to replace the tracking link in the emails within your SendGrid account itself. SendGrid includes a feature called Link Branding that functions the same as Apollo's Tracking Subdomain. This Link Branding feature provides the URL that you must replace to reset the deliverability on your account. For this scenario, contact SendGrid Technical Support so they can help you update this configuration and provide any additional information about deliverability within your account.

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Email Content and Formatting

  • Remove Links from the Body of Your Email: SPAM filters look for links, especially in first-contact emails. Your signature is scanned for links as well. Make sure you've removed links from your signature as well as in the body of your emails.
  • Remove Images from the Body of Your Email: Images or attachments, especially in first-contact emails, can activate SPAM blockers and cause bounces. Remove these assets and stick to text. Save your images and attachments for Step 3 or later in sequences once you've sent a few other emails. As with links, even images in your signature can cause issues.
  • Don't Apply Special Formatting to Your Text: Simply put, SPAM blockers scan for formatted text. Avoid using different colors, fonts, bolding, italicization, and underlining.
  • Keep Your Paragraphs Concise: Lengthy content can activate SPAM blockers or even cause bounces. Keep your wording simple and to the point.
  • Avoid Words that Trigger SPAM Filters: SPAM filters have evolved considerably in the past few years, and as such, there isn't a shortlist of words to avoid. In general, try to communicate in a professional, personable way and avoid words and phrases that sound suspicious, urgent, or needy. This HubSpot article provides a comprehensive list of words or phrases that you should avoid. As a best practice, ask yourself if the email you intend to send is one you would want to receive yourself.
  • A/B Test Your Messaging: Always test out your messaging to find what results in the highest engagement. You can A/B test in Apollo to try multiple versions of a similar message. If you find one version is blocked at a higher rate, you can look at the differences in your messaging to try to understand the cause.

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Additional Considerations

While the measures listed below are not required, following their guidance may help to limit bounces and SPAM blocking for the emails you send through Apollo.

  • Include an Unsubscribe Link in Your Email Signature: Apollo allows you to use whatever text/phrase you'd prefer in an opt-out link and automatically adds the link with your signature on all of the emails you send through the platform. Research shows that recipients are far more likely to use an unsubscribe link instead of marking your emails as SPAM. Marking your emails as SPAM can affect your overall sending reputation and is, therefore, a much worse outcome.
  • Deactivate Click Tracking: Click tracking manipulates links in emails, which SPAM filters can sometimes detect. Disable this feature if you're having issues by deactivating it in each user's profile. For additional information, please see the "Click Tracking in Apollo" article.

    Disable Click Tracking

  • Update Apollo Send Limits in the app. Head to Settings, click You, and then click the Mailboxes tab. Click the appropriate mailbox and amend the sending limits in the daily/hourly fields.

    Send Limits

  • Deactivate Open Tracking: The same technology for open and click tracking is usually very sensitive to filters in email servers. This makes them more susceptible to SPAM blockers. If this is something you've struggled with and you have followed the instructions provided above as best practice, you may want to consider disabling open tracking. For additional information, please see the "Open Tracking Overview" article.

    Disable Open Tracking

Going the Distance with Gmail

If you would like additional information about how to avoid having your emails SPAM blocked by Gmail, please see the "Prevent mail to Gmail users from being blocked or sent to spam" article in the Google Help Center.

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