Valid email address incurring bounce

Valid email address incurring bounce


Let’s assume you are a model email marketer. You have built your mailing list via double opt-in and you respect unsubscribe requests. Last but not least, you have also validated your email list with the MailboxValidator service and only send emails to those email addresses marked as valid. Imagine your shock when you send an email to a valid email address and get a bounce notification. What’s wrong with this picture?

Is something wrong with the validation process?

Your first thought might be that the MailboxValidator service must have made a mistake. But the fact is, you will only ever get a valid email result from the validator if the mail server itself responded with a valid indicator.

The email address might be a catch-all address

This is one of the likely reasons why you have incurred a bounce when sending an email to that address. That particular address or its domain has a catch-all configured. What this means is that, any email address for that domain will always show as valid when the MailboxValidator validator is performing the check with the mail server. But if you try to actually send an email to that email address, it will bounce. Therefore, we highly recommend not sending any emails to addresses where the is_catchall field is True.

Your mail server does not have DKIM or SPF

If you did not configure SPF (Sender Policy Framework) or DKIM (DomainKeys Identified Mail) for your mail server, some ISPs may choose to bounce any incoming emails from your domain. In this case, you will need to contact your email hosting provider to get them to configure said settings.

There is no PTR record for your mail server domain

A lot of mail servers these days are configured to check your email domain for the PTR record. If your DNS did not have a PTR record configured or if it’s incorrectly configured, your email will be bounced. Again, you have to talk to your email hosting provider to remedy this situation.

Your mail server IP or domain has been blacklisted

Being blacklisted can happen to even legitimate email marketers on occasion. You will need to check the MX blacklists and then request them to delist your mail server.


The above are just some of the possible scenarios which can cause emails to bounce. If you’re able to address some of the issues mentioned above, you should see your bounce rate dropping.

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