POP, IMAP, SMTP session limits

Session limits

Each email account is subject to a maximum limit of POP and IMAP connections that can be initiated on Qboxmail servers by the same IP address.

The values set by default are more than enough for a regular mailing traffic through an user's email client:

• 50 simultaneous sessions for IMAP;
• 10 simultaneous sessions for POP.

It may happen that this limit is reached. For example, if you configure the same email account on a multiple number of stations and, simultaneously, on various devices (like smartphones), and each account is connected to the same corporate connectivity. In this case, the problem manifests itself with an incorrect username and password. You can reset the number of active connections simply by closing and reopening your email client. If this procedure does not work, there might be other problems to be solved on your PC. It could be an antivirus. Or, it could be a firewall that does not close the sessions correctly, even after closing the email client, because TLS connections are blocked. You can usually find more information and directions on how to solve the issue on the website of your antivirus manufacturer.

You can analyze each email account log info on Tracemail. With this tool, you will be able to make sure that the issue of wrong username/password is actually provoked by a maximum number of connections reached.

To avoid this kind of issues, we advise you to configure your email account on a single PC and, if configured also on Smartphone and Tablet, to access through your personal data and not via Wi-Fi or ADSL. We also recommend that you assign each person a single personal email account (ex. john.doe@domain.com) and set up generic email accounts (info@, sales@, ...) such as Email Alias to individual personal email accounts.

Read our documentation on Email Alias to know more about this feature.

Thunderbird

If you use Thunderbird, you can change the number of open connections for each account in the settings: Settings > Server settings > Advanced > Maximum number of connections to the server to be kept in the cache (set it to 1).

MS Outlook

If you use MS Outlook, you cannot change the number of connections opened on the IMAP server. In this case, we advise you to remove the subscription to the IMAP folders that you do not use frequently and to set a control frequency for new messages between 15 and 25 minutes (this does not affect the notification of the arrival of new messages, which remains in real time). The error disappears immediately by closing the email client because the connections are immediately closed on the side of the server, too.

If the error persists, contact our technical support by opening a Ticket to perform an in-depth analysis.