The 100 migration batches limit and how to not run into it

As you might or might not know, in Exchange Online we have an upper limit of 100 migration batches. You can see this limit for MaxNumberOfBatches in the Exchange Online PowerShell Get-MigrationConfig: (To understand the MaxConcurrentMigrations limit of 300, you can check this blog post written by one of our migration experts, Brad Hughes.) 100…


Troubleshooting IMAP Migrations to Office 365

During my day to day work as a part of support organization, I work with and help troubleshoot mailbox migrations very often. One type of migrations that we see quite often is IMAP migrations. I wanted to put together an overview of IMAP migration good practices as well as troubleshooting tips related to IMAP migrations….


Introducing the Exchange Online Fiddler Extension

Working in support at Microsoft, you get to deal with a lot of organizations who are migrating to Exchange Online. This type of migration dramatically changes how web traffic flows in the organization as the traffic moves away from Exchange on the Local Area Network to servers hosted by Microsoft in a Microsoft Data Center,…


Resource Based Throttling and Prioritization in Exchange Online Migrations

We often get questions about throttling in Mailbox Replication Service (MRS) based migrations in Exchange online. When migrating, you may see messages such as StalledDueTo_TargetDiskLatency for some periods of time. These messages come from our resource-based throttling infrastructure in Exchange Online. This is how this would look like in the output of Get-MoveRequestStatistics: PS C:\>…


Best practices for using assigned Office 365 DNS records

As someone who reads through hundreds of support cases each month, nothing pains me more than seeing customers struggling with seemingly complex issues, only to discover that the root cause is quite simple. Never is this truer than it is with DNS. Some of the most complicated security and lost mail issues boil down to…


New Message Trace in Office 365 Security & Compliance Center

Overview Message Trace is a key tool for email admins to troubleshoot and track the health of their organization’s mail flow. Message Trace in the Exchange Admin Center (EAC) is a useful tool for tracing messages, but it’s visually cluttered and confusing, and it lacks a number of more sophisticated capabilities. To make Message Trace…


OffCAT’s replacement – Microsoft Support and Recovery Assistant (SaRA)

After over five years of providing configuration information and solutions to known issues, the OffCAT team is planning to remove OffCAT from the Microsoft Download Center on May 31, 2018. The good news is that core OffCAT features have been consolidated with the Microsoft Support and Recovery Assistant for Office 365 (SaRA) tool at https://diagnostics.outlook.com/….


Demystifying Hybrid Free/Busy: Finding errors and troubleshooting

In this second part of the Demystifying Hybrid Free/Busy, we will cover troubleshooting of Hybrid Free/Busy scenarios, more specifically – how and where to find an actual error that will indicate where the problem is. Before venturing forth, please make sure that you have seen Part 1 of this demystifying series! Here is the graphics…


Demystifying Hybrid Free/Busy: what are the moving parts?

Hybrid Free/Busy is one of those things that many people do not fully understand. If everything works well, the complexity is hidden from view and people working in various parts of organization can seamlessly work together. But if things go wrong… you will appreciate deeper understanding of what makes it work. This is why we…


Exchange Log Collector Script

A while ago I created the “CollectLogsScript” (see my old A better way to collect logs from your Exchange servers blog post) which I have since rebranded to “ExchangeLogCollector”. Seeing that this has proven popular, I have continued to make some major improvements to the script over the years. The script was recently moved over…