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If you’re a high-volume sender (5K+ subscribers) and have been sending gradually and frequently to your subscribers while your list has grown, you can happily skip this post. However, if your list of subscribers is over 5K and you find yourself in one of the following situations, you may want to keep reading to ensure you manage your sender’s reputation.

  1. You are new to bulk campaigns.
  2. You haven’t been emailing/engaging with your subscribers frequently.
  3. You switched your sender domain, email address, outbound IP, or provider.

Why do we need to be careful?

ISPs are on the lookout for sudden bursts of activities in order to catch malicious senders as this activity often indicates a non-opt-in, purchased, or harvested list. If you are sending 50 emails one day and 5K emails the next, you’re going to be flagged as suspicious and your emails will be directed to the recipient’s spam folder.

What to start with?

You should gradually build up your sending volume over time. A suggested volume would be 1K emails per day, sending only high-quality content and ensuring your list is clean.


Recipient engagement is really important when it comes to sender reputation. If your users are not engaging and you are not removing disengaged recipients from your list, you are going to damage your sender’s reputation over time. That’s why we recommend segmenting your lists and campaigns from the get-go to make them more personalized. Depending on the type of emails you are going to send and your industry, there are many different ways you can segment your mailing list.


Age, gender, occupation, industry, location

Customer information

A new user or buyer, a frequent user or buyer, a free-trial subscriber, a non-converter


The time emails are opened, last purchase, recent web activity, interest levels

Type of email

Are you targeting openers or targeting inactive users?

If you are new to bulk campaigns, you may also want to consider using an external SMTP provider to remove ISP limits and improve deliverability. Reach out to our award-winning support team at hello@smtp2go.com for further information and advice.

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