Number of users / Billing mailbox / Callout

MailCleaner Support
Added over 8 years ago

Your MailCleaner statistics doesn't display the correct number of mailbox used? Don't panic !
The number of mailbox is not the final number of billing. It can be modified at any time in your billing interface.

Some explanations:

  • Some domains configured by our customers have no callout configured and according to the type of authentication for users, some attacks can simulate users who don't exist. When the callout is not configured for example, an attacker will try to send spam to anyone on the domain and if the callout isn't configured your mail server will receive these mails. For each incoming mail, MailCleaner recognizes this as a new user (even Spammers send mail to addresses like,, or all common names:, etc.

Most of the time, the number of mailbox is incorrect because of this missconfiguration. To test the configuration of your callout: Configuraton > Domain > MyDomain and select Adress verification and click Test configuration.

You can test manually your callout configuration with a telnet SMTP session and at the rcpt to: jhgfhgadsljhksjhkdha@yourdomain.tld (a non existing user of your destination domain), you should receive a 550 User unknown. If you receive a 250 Recipient ok , your callout is not working, your server is not configured according to the RFCs for SMTP, or you have configured a catchall address.

It is really important to solve this issue and have a working callout, to protect your and our infrastructures from attacks.

For questions regarding Exchange server configuration for Callout compatibility, please read our documentation:

For questions regarding billing and number of mailboxes, you can directly contact our sales department: