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How Mail250 calculates bounce rates

Bounce Rate = (Number of emails for which bounce is received/Number of emails which Mail250 attempted for delivery)*100

Bounces occur when an email can’t be delivered to a particular email address. There can be multiple reasons for this non-delivery of emails. For the simplicity perspective, these reasons are globally categorized under;

Hard bounce
Soft bounce

What is Hard bounce?

Hard bounces happen when an email can’t be delivered. This is mostly a permanent bounce, so any reattempt within a stipulated period will mostly reason in hard bounce only.

The most common reason for these hard bounces is an invalid email address (which the recipient’s mail server is unable to recognize), or in some cases, it’s the unexpected response while making a delivery attempt on the recipient’s mail server.

What is Soft bounce?

Unlike Hard bounces, in case of Soft bounces, the email server is actually able to recognize the email address but still returns a bounce notification to the sender because the recipient’s mailbox is either full or temporarily unavailable.

High bounce rates

High bounce rates are mostly because of a totally invalid email address which either doesn’t exist or the recipient’s mail server is invalid.

Every Internet Service Providers (ISPs) have their thresholds for bounces and complaints from a particular sending IP address and domain. If the bounce or complaint rates are too high, your Mail250 account might go for a manual review with the compliance or may lead to permanent termination of your account.

Bounce rate thresholds are not fixed and vary between ISPs and mailbox providers and it keeps getting updated based on the incoming volume and engagement trend with the emails.

Generally, ISPs and mailbox providers don’t share their thresholds publicly. This is primarily to avoid sharing too much information with any potential spammers.

At Mail250, it is recommended to send emails below a 10% bounce. This is just a recommendation based on the global best email practices and doesn’t necessarily guarantee any potential reputation drop or suspension of your account.

How to avoid bounces

If you haven’t sent an email in a while, try to reconfirm your list of email addresses by sending them a Hi message or ask them to reconfirm their email addresses on your website/app.

This will help you protect the list from spam traps and fake signups that lead to high bounces.


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