Adding Custom Domain Names to Office 365

Due to the multi-tenant nature of office 365, all the tenants in Office 365 by default have a domain name like <Company Name>

  • The customers would like to retain their email address domain name even after migration to Office 365
  • When we migrate mailboxes from On-Premises to Office 365, one of the first steps involved is to add the domain name (SMTP domain) of the customer in Office 365.

This article describes the step by step approach to add a custom domain name to Office 365 tenant.

First navigate to Office 365 admin center with the URL

The interface of Office 365 has been recently upgraded and I am have followed the latest UI in this article.


We need to select “Add Domain” option either from “Home Screen” of “Office 365 Admin Center” or from the “Settings” option in the left pane of “Office 365 Admin Center”





After we click on “Add domain”, we get the below console where the default Office 365 domain name is present. In this case, it is Click on “Add domain” button in the below console.



Now the “New domain” wizard appears. It is a fairly simple process in which the below steps are carried out.

  1. Add our custom domain name
  2. Verify that the domain name is owned by the tenant
  3. Setup online services like Skype, Sharepoint, Exchange etc
  4. Update relevant DNS records

In this case, I am entering the domain name as “” which is a domain I own.



Now the critical part of verifying the domain name comes to picture. We cannot add a domain name to our tenant unless until we own that particular domain.

Hence we need to verify/prove that we own the domain name via below methods.

  1. TXT record
    1. By adding a custom TXT value presented in “New Domain” addition wizard on the DNS server of the domain we own. In most cases, we can update the TXT record via browser. In our demo, we will be adding which is a domain name provided by and I own that particular domain.
  2. MX record
    1. This option can be used if we have currently published an MX record under the domain name. This is mostly used if an existing On-Premise Exchange server uses the domain name we are trying to add to the Office 365 domain.

We are going with the first option of verifying the domain name using TXT record.

We need to add the below TXT record (MS=ms31321414) to the DNS server where is hosted. Also the TXT record would vary for requests from individual tenants and hence it is unique to your domain.


Before we click on the “Verify” button, we need to add the TXT record in the Internet DNS server. I am going to add the value as given in below snaps which are taken from since is provided to me by WordPress.

Note: You can always click on Your DNS host” (highlighted in blue in above snap) to check for the various DNS hosts directly supported by Office 365 which will make your domain verification much easier. Unfortunately, WordPress provider is not one among them and hence we do all the steps in this demo manually.


Adding TXT records in’s DNS server for



Once the TXT record is added, click on the “Verify” button under “Verify domain” window mentioned in Step 4.


Once the domain name is verified, we need to setup the various DNS records for all the services/offerings provided by Office 365. If we don’t register the below records, the internet mail delivery to the custom domains would be affected.


Since I have a website with, I am going to update the DNS records manually. In most cases if you have purchased the domain from GoDaddy, MyHosting etc, you can go with first option and authorize Office 365 to make the changes directly on the DNS server which is a very easy process.

Records Needed for Office 365 Services:



Records added in DNS server:


For adding records, I have just repeated the steps mentioned in Step 5 but chosen appropriate record types like A, CNAME, SRV etc as mentioned in the above snap.

Voila 🙂 We are done 🙂

Final snaps after the DNS records are updated.


In this article, we have learnt how to add a custom domain name to an existing Office 365 tenant.

What is Office 365 ?

What is Office 365 and the growth of Office 365:

Cloud computing is the buzz word in IT industry now. Every major IT product company is trying to provide the best cloud solutions to its consumers.

Cloud computing can be classified into the below 3 models.

  1. IaaS [Infrastructure as a Service]
  2. PaaS [Platform as a Service]
  3. SaaS [Software as a Service]

A great Cloud offering under the model SaaS from Microsoft is “Office 365”.

In the recent days, I found lot of misconceptions about Office 365 among the Exchange admins and the end users alike.

One of my friends recently asked “what is Yammer?”. One of the organizations recently provided Office 365 business plan subscriptions to its employees and many asked if it would allow them to access mails in their mobile device because the very word cloud means mobile access to many. Most Exchange admins feel that Office 365 is only Exchange Online and they often fail to understand the underlying AD Azure.

So in my words, here it goes ….

Office 365 is a brilliant cloud offering from Microsoft which refers to “subscription plans” that include access to “Office Applications” and major “Productivity Services” that are enabled over the Internet (cloud services) like Exchange Online, Lync Online, Sharepoint Online, OneDrive for business etc.

From an enterprise IT admin perspective, Office 365 has two major classifications:

  1. Business
  2. Enterprise

Business plans basically provide access to Office Applications via Internet to the business users. The applications can be installed (Click To Install over Cloud) in one or more devices (smartphone, tablet & computers) or accessed online via various browsers like IE, Chrome, Safari etc. The office applications included are MS Excel, MS Word, MS PowerPoint, OneDrive and MS Outlook. (Skype for business & OneNote are included in some plans)

Enterprise Plans provide both Office applications & Productivity services over internet. The productivity services from Office 365 are Exchange Online, Lync Online, SharePoint Online, Delve (Information Discovery within Office 365), Sway (Digital story telling app), Yammer (Social network in a professional environment similar to “Facebook At Work”) & OneDrive for business (Cloud Storage like DropBox).

Hence an organization can use Office apps from Office 365 subscription & the email service can be from On-Premise Exchange Server 2013. Some organizations can completely use Office 365.

The authentication for Office 365 users are provided by Azure Active Directory (AAD) similar to Exchange users getting authenticated by On Premise Domain Controllers running Active Directory.

More info on …

Growth of Office 365:

Cloud offerings from Microsoft has picked up a great momentum in the last financial year and it is growing even faster this year. In the last 2 years, I have witnessed 80,000+ mailboxes of an IT organization getting migrated to Office 365 within 6 months and one more organization embracing Office 365 Office apps for the whole organization. A humongous scale of adoption for MS cloud platform clearly indicates the reliability, scalability, business continuity provided by Microsoft Cloud Platform.

The earnings release data from Microsoft release for Q1 FY16 clearly shows the industry acceptance trend for Microsoft Cloud offerings like Office 365 & Azure. A few Excerpts are given below.

  1. Office 365 consumer subscribers increased to 18.2 million, with approximately 3 million subscribers added in the quarter
  2. Office commercial products and cloud services revenue grew 5% in constant currency with Office 365 revenue growth of nearly 70% in constant currency and continued user growth across our productivity offerings
  3. Commercial cloud annualized revenue run rate exceeds $8.2 billion

With fast track deployments and easy to migrate options, Office 365 is equally embraced by Start Ups in India and enterprises across the globe. Thus Exchange Administrators like me are all geared up to embrace cloud faster than ever before having 18.5 million users already in Office 365!

Why wait to experience Office 365 …. Follow the below link …

Office 365 Guide for Exchange Admins