Outlook connectivity: Troubleshooting and solving common issues

Outlook is one of the most-used client applications by organizations around the globe. Office 365 is in high demand in many countries and there is considerable excitement about running the latest version of Outlook, which is Outlook 2019. But amid the excitement, there is frustration: Many are struggling with Outlook connectivity issues. This problem not only affects clients connecting to the cloud but all customers who are still running on-premises versions of Exchange like Exchange 2010 or higher. What is causing these Outlook connectivity issues? It can be any one of the following:

  • Lack of bandwidth
  • Older Outlook clients
  • Migrations gone wrong
  • SCP records not cleaned up
  • DNS issues or stale records or double Autodiscover records
  • Firewall issues
  • Antivirus issues

Let’s take a look at each one of the items listed above and talk about them -- and if you are having a problem, hopefully, we can get you up and running.

Bandwidth and Outlook connectivity

Speed is a big factor for Outlook clients as they are sensitive to network blips or slowness. Imagine being on a 1MB ADSL line with 20 people trying to connect. This will cause a lot of frustration, not only connecting to Office 365 but also to a datacenter where mail is hosted. In some countries, bandwidth is very expensive and companies pay a fortune to get good quality lines. That in turn means more costs to apply QOS (quality of service) so that the end-user has a great experience on Outlook, as in some companies the SLA for email is very high.

Older Outlook clients

With the newer versions of Outlook comes newer licensing costs and increased costs for buying the application. Companies tend to stick with the legacy clients and not upgrade quickly due to the increased cost of software. Older clients like Office 2010, which will have support ending in January 2020, are going to force companies to upgrade to newer versions of Exchange because Office 365 will not support these older versions. The older clients also use RPC of HTTP, which is the older protocol and newer clients and Exchange use MAPI over HTTP to connect.

Ensure that your clients are up-to-date and patched. Missing patches can also cause disconnects in the older clients and you should follow what Microsoft sets out. An example would be to have a certain hotfix and patch loaded to ensure optimal client connectivity to either an on-premises solution or Office 365. And be sure to keep an eye on the support pages for both as Microsoft does update them.

Migrations gone wrong

Sometimes you work with ISPs and migrations for clients don’t always go as planned. This can be due to DNS records not being changed (more on this below) or because Outlook clients have ingested data but it is taking very long so the Outlook client is slow or the backfill never completes due to cost or licenses running out for migrations. Be sure to make your clients aware of the cost for migrations and also do staged migrations so that clients don’t experience the slowness. If possible, do them over a weekend when it is quiet.

DNS records

This is always a big problem when it comes to client connectivity. Outlook clients will query internal first before they go external. If you have migrated your on-premises Exchange to Office 365 or brand of choice, be sure to clean up the records you have not only internally but also externally. This ensures that clients do not try to query the wrong thing and end up with popups or being disconnected.

Sometimes when clients migrate from an ISP to a hosted company or from an ISP to Office 365, there is that Autodiscover record that tends to linger behind and cause issues.

Firewall issues

Almost all clients are running some form of a firewall. This can be a legacy TMG solution or an F5 load balancer acting like the firewall or SonicWall, and sometimes they are not configured correctly. This means not all ports are open for client connectivity or the firewall has not been updated to adjust for the newer versions of Exchange on-premises or connecting to Office 365.

Be sure to keep your firewall updated to support the newer versions and keep the rules on the firewall clean so you don’t run into any issues.

Antivirus issues and Outlook connectivity

An antivirus is great in keeping the bad out, but sometimes the product, if not configured correctly, can cause more issues to an Outlook client than not having it. Different symptoms might be that mail is sent to the wrong folder as it is flagged incorrectly or Outlook is disconnected as the antivirus blocks all communication. You need to make sure that you configure the antivirus product correctly as per the vendor to ensure that end-users don’t end up with more hassles. There are also applications that you can use to troubleshoot client connectivity. Let’s take a look at some of those.

Applications for troubleshooting Outlook connectivity

  • Fiddler
  • WireShark
  • Microsoft Test connectivity website

Fiddler is a great tool if you need to deep-dive into an Outlook that won’t connect. But a word of caution: This tool displays the details in plain text and can be used to “sniff” traffic.

WireShark will capture network traffic. Sometimes you have a remote branch that routers don’t know how to get out or a network change was done and traffic is not flowing as it should. This tool is great for seeing how traffic flows on the internal network.

The Microsoft Test connectivity website was designed by some very smart guys. This website allows you to test protocols like ActiveSync, OWA, and Autodiscover to check your Outlook connectivity.

Featured image: Shutterstock

Edward van Biljon

Edward van Biljon is an experienced messaging specialist working in the IT and services industry. He is skilled in WSUS, domain name system, datacenters, printer support, and System Center Configuration Manager (SCCM). He has a background as a strong IT professional and has an international diploma in programming focused on computer programming.

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