What is exchange server? 

Exchange server is a platform created by Microsoft for emailing, contacting calendaring, collaborating, and scheduling. Exchange Server is known for its High Availability (HA) features. These features secure a continuing service in case of possible outage scenarios. 

Users can purchase either Exchange Server Standard for small businesses or Exchange Server Enterprise for bigger businesses. More information about the two will be provided later on in the article.  

Exchange Server: versions  

There have been a lot of Exchange Server versions since the first version came out in 1996. The, at this moment, unsupported versions in chronological order are: 

  • Microsoft Exchange Server 4.0
  • Microsoft Exchange Server 5.0
  • Microsoft Exchange Server 5.5
  • Microsoft Exchange Server 2000
  • Microsoft Exchange Server 2003
  • Microsoft Exchange Server 2007
  • Microsoft Exchange Server 2010
  • Microsoft Exchange Server 2013 

Apart from these unsupported versions there are 2 supported versions as well. These are Microsoft Exchange Server 2016 and Microsoft exchange server 2019.  

Microsoft Exchange Server 2016 

Exchange Server 2016 was released on October 1st, 2015. Since most Exchange Server versions are supported for around 5 years, the mainstream support for Exchange Server 2016 ended on October 13th of 2020. However, the extended support stops on October 14th of 2025. This means that Exchange Server 2016 only receives reliability and security updates and bug fixes.  

Microsoft Exchange Server 2019 

Exchange Server 2016 was released on October 22nd, 2018. The mainstream end of support date is, like the previous version, already surpassed. On January 9th, 2024 the Mainstream support was replaced for the extended support which is still ongoing until October 14th of 2025. As for Exchange Server 2019, the same rules regarding the support apply. Owners of the license will only receive reliability and security updates and bug fixes.  

Microsoft Exchange Server 2025  

Exchange Server 2025 doesn’t exist at the moment but is the newest version of Exchange Server that will be released in the second half of 2025. Exchange Server 2025 will be released as a subscription only. These subscriptions will comply with Microsoft’s Modern Lifecycle Policy which means Microsoft is obliged to inform its users 30 days in advance if they’re supposed to act in order to avoid a decrease in the quality of their product. Additionally, Microsoft has to let its users know when there are plans to end the support 12 moths in advance.  

Exchange server: editions 

Exchange Server Standard 

Exchange Server Standard is the most basic Exchange Server edition. It includes a maximum of 5 mounted databases per server and a limited database size of 1024 GB. Mounted databases are databases that are in use. For small businesses it would make more sense to acquire Exchange Server Standard to keep costs as low as possible.  

Exchange server Enterprise 

Exchange Server Enterprise is the more extended Exchange Server edition. It comes with a maximum of 100 mounted databases per server and a limited database size of 16Tb. Purchasing Exchange Server Enterprise makes more sense for bigger organizations since the number of mounted databases and the limit of the database are considerably higher and therefore is costs as well.  

Exchange Server: requirements 

Since there are only 2 supported versions left, the requirements of Exchange Server 2016 and Exchanger Server 2019 will be displayed below.  

Exchange Server 2016 

  • Minimum operating system: Windows Server 2012 R2.
  • Minimum of 2 CPUs with 2 cores each.
  • Minimum memory of at 8GB. 
  • At least Windows 2008 Active Directory Forest Functional Level 

Exchange Server 2019 

  • Minimum operating system: Windows Server 2019.
  • Domain controllers in an Active Directory are required to run at least Windows Server 2012 R2.
  • Hosting Server must be a 64-bit processor.
  • Hosting Server must have between 128 GB and 256 of RAM.
  • AD forest function level must be at least Windows Server 2012 R2. 
  • Must have New Technology File System (NTFS).  

How to license Exchange Server? 

Earlier in this article was stated that users can purchase Microsoft Exchange Standard or Microsoft Exchange Enterprise. Moreover, CAL features can be acquired. If users want to enable Standard CAL features, being licensed with the Standard CAL is a requirement. If users want to enable Enterprise CAL features, being licensed with the Standard CAL and the Enterprise CAL is a requirement. 

Regarding CAL licensing there are two options; User CALs and Device CALs. Depending on which of these two is less represented within an organization, management can decide on which of these two different licenses to purchase. If an organization has more users than devices. Financially, it would make more sense to purchase Device CALs because purchasing a license for every employee wouldn’t make sense since there are not enough devices for the number of users. So, if all devices are licensed, different employees can use these devices at different times.  

If, on the other hand, an organization has more devices than users, it would make more sense to purchase User CALs so all users have their own license which they can use on all the different devices that they’re using instead of having to purchase a license for all of these devices which would mean a lot more costs.