Troubleshooting the "Concurrent Connections Limit Exceeded" Error in Bold BI Scheduled Executions

Issue Overview

When using Bold BI to send scheduled reports via email through SMTP servers, you may encounter the following error: "4.3.2 concurrent connections limit exceeded."

This error typically arises when multiple scheduled reports attempt to send emails simultaneously, exceeding the allowed number of concurrent SMTP connections.

Root Cause

This issue is not specific to Bold BI. It stems from Microsoft Exchange Online's limitations on SMTP connections. Microsoft enforces a cap on the number of simultaneous connections that can originate from a single client or IP address.

In scenarios where Bold BI tries to send several emails at once—such as during scheduled report executions—these limits may be exceeded, resulting in the error message.

Resolution Options

To resolve this issue, you can choose one of the following approaches:

Stagger Scheduled Report Times

Avoid sending all reports at the same time. For example, if you have 10 reports scheduled for 9:00 AM, consider staggering them at 5-minute intervals (e.g., 9:00 AM, 9:05 AM, 9:10 AM, etc.). This reduces the number of concurrent SMTP connections and helps prevent the error.

Use Microsoft Office 365 with OAuth2 Authentication

Instead of traditional SMTP, Bold BI supports sending emails via Microsoft Office 365 using OAuth2 authentication. This method offers several advantages:

1. Avoids SMTP connection limits
2. More secure: Uses token-based authentication
3. Better integration with Microsoft 365 services
4. Supports modern authentication protocols

Steps to Configure Microsoft Office 365 in Bold BI

1. Navigate to http://{your-domain}/bi/site/site1/administration/e-mail-settings
2. In the Email Account dropdown, select Microsoft Office 365.
3. Enter the Sender Email Address that has the Mail.Send permission via Microsoft Graph API.
4. Ensure OAuth is selected as the authentication type.
5. Fill in the following fields:
   1. Tenant ID
   2. Client ID
   3. Client Secret
6. Click Test Connection to verify the setup.
7. Once verified, click Save.
8. To confirm the configuration, enter a recipient email address and click Send.

For more information, you can refer to our help documentation.

Recommendation

We strongly recommend using Microsoft Office 365 with OAuth2 for email delivery in Bold BI. This approach not only resolves the "4.3.2 concurrent connections limit exceeded" error but also enhances security and reliability.

Additional Details

• Email with Microsoft Office 365 OAuth2 | Bold BI Docs