I explained that, for security reasons, messages sent from outdated on-premises Exchange servers over an inbound connector of type OnPremises would soon face throttling and blocking. If your outdated on-premises connecting servers encounter throttling or blocking, you’ll see one or both of these errors in your on-premises email logs:
4.7.230 Connecting Exchange server version is out-of-date; connection to Exchange Online throttled for n mins/hr.
5.7.230 Connecting Exchange server version is out-of-date; connection to Exchange Online blocked for n mins/hr.
My customer was facing the following issue:
We are experiencing issues with sending emails. It seems we might be missing outgoing emails, and I've been waiting for replies that haven't arrived. This issue is affecting all users, not just my account.
What did I do?
1. I checked the Exchange setup. It was a hybrid environment with two Exchange Server 2016 instances running CU19 from 2020.
2. I logged on to Exchange Online. In the EAC navigate to Reports > Mail flow > Out-of-date connecting on-premises Exchange servers
Solutions:
There are two solutions.
- Enforcement pause (Temporary Solution)
- Install the most current Exchange Server Cumulative Update (CU)
Solution 1: How to create an enforcement pause
Using the Exchange Admin Center (EAC)
⦁ In the EAC navigate to Reports > Mail flow > Out-of-date connecting on-premises Exchange servers
⦁ In the report click on the Enforcement Pause link located on the right side just above the bar chart:
⦁ Click on enforcement Pause, enter the number of days you would like to pause, then click Save. Remember, you can only pause enforcement for a total of 90 days per calendar year per tenant.
Solution 2: Install the most current Exchange Server Cumulative Update (CU)
You can find the CU here:
Warning: Updating an old Exchange Server can be tricky and may lead to problems, so make sure you have time to fix any issues that might come up.
Click here> How to Upgrade Exchange to the latest CU
Conclusion:
In this blog, we have delved into the steps required to resolve the issue of connecting to out-of-date on-premises Exchange servers. Additionally, we discussed best practices for maintaining server health and ensuring seamless connectivity in the future.