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Directory Synchronisation

What is Global Address List Synchronisation (and why would I need it?) 

What is Global Address List Synchronisation? 

A Global Address List (GAL) is a comprehensive directory of all email users, distribution groups, and contacts within an organisation’s email system.  

To an end user, the GAL appears as an address book that is integrated into their email client, such as Microsoft Outlook.  

When composing an email, users can access the GAL to search for and select recipients, view contact details, and ensure they are reaching the correct individuals or groups within the organisation.  

GAL synchronisation refers to the process of ensuring that the address books (contact directories) of different email systems are consistent and up-to-date.  This ensures everyone can easily find the correct email address of someone they need to reach, even if they are using a separate email system. 

Here’s the main reasons why you might need a tool to help with GAL synchronisation: 

  1. Your company has just merged with, or acquired a separate company: When organisations merge or acquire other companies, they typically inherit a bunch of separate email platforms. This might be totally separate Microsoft 365 tenants or on-prem Exchange servers. A GAL sync tool automates the propagation of email addresses across these separate systems, ensuring everyone can communicate with each other in the ‘new entity’. 
  2. It helps keep contact information accurate: Manual updates to contact information can be error-prone and time-consuming. Let’s say someone gets married and changes their email address. GAL synchronisation tools can automatically transmit any such updates to all directories concerned.  This reduces the likelihood of errors and leads to improved communication efficiency and reliability. 
  3. There’s high security between different parts of your company: Some organisations need to maintain exceptionally tight security between different parts of the organisation.  A GAL Sync tool with the requisite security controls (e.g., encryption) can allow limited address list updates to take place to facilitate communications where necessary. 
  4. It improves collaboration: By having a synchronised GAL, employees can easily find and contact colleagues, partners, or clients across different systems, fostering better collaboration and teamwork. 
  5. It reduces administrative overheads: Automating the synchronisation of multiple GALs reduces the administrative burden on IT departments, allowing them to focus on other critical tasks while ensuring the address list remains accurate and up-to-date. 


In summary, a GAL sync tool is essential for maintaining an efficient, unified, and accurate contact directory within organisations, especially those with multiple new and legacy email platforms or those undergoing mergers and acquisitions. It enhances communication, collaboration, and overall organisational efficiency. 

Some GAL sync tools can also help you operate using a new email domain for the ‘outside world’, whilst you still have multiple legacy domains to deal with.  

So, for example, if your new entity becomes newcompany.com ‘overnight’, the original companies can still be operating as oldcompany.co.uk, previousco.de, originalco.com, etc., but can communicate using the new entity email address from ‘day 1’.

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