What is a spam sender?


In email marketing, a spam sender is an abusive email sender who sends repetitive, unsolicited, and/or irrelevant messages to people who didn’t consent to receive them. These domains may promote products or services in an intrusive and misleading way.

If your audience’s inbox providers flag your brand’s email domain as a spam sender, this will harm your email deliverability rates

How to avoid being flagged as a spam sender

To prevent your brand’s email address from being labeled as a spam sender, follow these steps:

1. Use a recognizable sender name

Make sure your brand uses a clear and recognizable sender name in your email address. You can do this by using a custom sending domain rather than a generic one assigned by an inbox provider like Gmail. 

When you use a custom domain, your email address is displayed as info@yourbrandname.com, for example. This helps subscribers immediately identify your emails and know they’re safe to open and engage with.

2. Authenticate your email domain

Authenticating your email domain verifies that your messages come from your brand.

To authenticate your email, implement authentication protocols like SPF, DKIM, or DMARC to:

  • Prove your emails are sent from authorized servers
  • Attach a digital signature to your emails
  • Protect your emails from spoofing attempts

3. Create a consistent sending schedule 

Inbox providers use spam filters that monitor irregular sending schedules and message volume. If you send too many emails simultaneously, these filters could flag your domain and impact your deliverability rate. 

You can avoid triggering spam filters by sending your messages on a regular basis—not in large, irregular batches.

4. Only engage with subscribers who want to engage with your brand

If your audience frequently receives irrelevant messages from your brand, they’ll be more likely to mark them as spam. If this happens often enough, your brand’s email address could be flagged as a spam sender.

To make sure recipients definitely want to receive your emails and provided you with the right email address, use double opt-in to obtain your subscriber’s express consent to receive your messages. 

To avoid sending irrelevant emails to your audience segments, use segmentation or personalization to speak more directly to your audience.

And if you notice some recipients have never engaged or stopped engaging, use a sunset flow strategy to win them back before scrubbing them from your list.

5. Monitor your domain’s reputation

Email blocklists track domains with poor sender reputations and high bounce rates. If your domain ends up on these lists, your email domain will likely be flagged as a spam sender.

Monitor email blocklists to make sure your domain isn’t listed. If it is, resolve the issue by:

A reliable marketing automation platform like Klaviyo can help you implement deliverability best practices to maintain a good deliverability rate and sender reputation. 

Klaviyo helps you create double opt-in sign-up forms to obtain express consent from your subscribers. Use reporting and analytics to monitor engagement metrics and make data-driven decisions that improve your email deliverability.

Ready to boost your email deliverability and protect your sender reputation? Sign up for Klaviyo today.

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