Note: We track email bounce rate for any campaign when you use Omnibasis SMTP service. We use AWS service to send email to guarantee the email delivery. 

Why do you care about my bounces?

High bounce rates are often used by entities such as ISPs, mailbox providers, and anti-spam organizations as indicators that senders are engaging in low-quality email-sending practices and their email should be blocked or sent to the spam folder. 

What should I do if I receive a notification stating that my account is under review or that my sending is paused because of my account's bounce rate?

Identify the cause of the issue, and then correct it. After you make changes that you believe will resolve the issue, send an email via support portal at with the name of your business account on Omnibasis. In your message, provide detailed information about the steps you've taken to resolve the issue, and describe how these steps prevent the issue from happening again in the future. Also include the following information:

  • The method you use to collect emails from your users and customers;

  • How you ensure that the email addresses of new recipients are valid prior to sending to them. 

What types of bounces count toward my bounce rate?

When an email is rejected by an email server, it's called a bounce. There are different types of bounces that depend on the reason the email bounced.  

Hard Bounces

A hard bounce indicates a permanent reason an email cannot be delivered. Hard bounced email addresses are flagged for your contact immediately and will need to be verified to be used again. Flagged email addresses will be excluded from all future campaign messages. Here are some common reasons an email may hard bounce.

  • Recipient email address doesn't exist.
  • Domain name doesn't exist.
  • Recipient email server has completely blocked delivery.

Soft Bounces

Soft bounces typically indicate a temporary delivery issue and are handled differently than hard bounces. When an email address soft bounces, it will immediately display as a soft bounce in the campaign report.

If an email address continues to soft bounce in additional campaigns, the address will eventually be considered a hard bounce and flagged as needs verification. We'll allow up to 15 soft bounces for contacts before converting a soft bounce into a hard bounce. While there are many reasons an email address may soft bounce, these are some common reasons this could happen.

  • Mailbox is full (over quota).
  • Recipient email server is down or offline.
  • Email message is too large.

Note: Your bounce rate includes only hard bounces to emails. Hard bounces are permanent delivery failures such as "address does not exist." Temporary and intermittent failures such as "mailbox full," or bounces due to blocked IP addresses, don't count toward your bounce rate.

What is the bounce rates that could cause my account to be placed under review or that could cause my sending to be paused?

For best results, you should maintain a bounce rate below 2%. Higher bounce rates can impact the delivery of your emails.

If your bounce rate is 5% or greater, we'll place your account under review. If your bounce rate is 10% or greater, we might pause your account's ability to send additional email until you resolve the issue that resulted in the high bounce rate.

Over what period of time is my bounce rate calculated?

We don't calculate your bounce rate based on a fixed period of time, because different senders send at different rates. Instead, we look at a representative volume—an amount of email that represents your typical sending practices. To be fair to both high- and low-volume senders, the representative volume is different for each user and changes as the user's sending patterns change.