List of attributes that are synchronized to Office 365 and attributes that are written back to the on-premises Active Directory Domain Services

This article lists the attributes that are used by directory synchronization in Microsoft Office 365. This contents of this article are as follows: 

• Table 1: Attributes that are synchronized from the on-premises Active Directory Domain Services (AD DS) to Office 365
• Table 2: Attributes that are written back to the on-premises AD DS from Office 365 in an Exchange rich-coexistence scenario
• How directory synchronization determines what is not synchronized from the on-premises environment to Office 365

Table 1: Attributes that are synchronized from the on-premises Active Directory Domain Services (AD DS) to Office 365

The following table lists the attributes that are synchronized from the on-premises AD DS to Office 365. Be aware that objects must contain values in the following attributes to be considered for synchronization:

• cn
• member (applies only to groups)
• samAccountName (applies only to users)
• alias (applies only to groups and contacts)
• displayName (for groups with an mail or proxyAddresses attribute populated)

Table 2: Attributes that are written back to the on-premises AD DS from Office 365 in an Exchange rich-coexistence scenario

The following table lists the synchronized attributes that are written back to the on-premises AD DS from Office 365 in an Exchange rich-coexistence scenario. These attributes are written back only if Exchange Federation for Rich-Coexistence is enabled for the organization.

How directory synchronization determines what is not synchronized from the on-premises environment to Office 365

This section contains information about how directory synchronization determines what is not synchronized from the on-premises environment to Office 365.

Contact objects:

• contains "MSOL" in DisplayName
  
• msExchHideFromAddressLists = TRUE

SecurityEnabledGroup objects: 

• isCriticalSystemObject = TRUE
• mail is present AND displayName is not present

MailEnabledGroups and MailEnabledContacts objects:

• (proxy addresses does not have a primary SMTP address) and (mail not present/invalid - i.e. indexof('@') <=0)

iNetOrgPerson objects:

• sAMAccountName is not present
  isCriticalSystemObject = TRUE

User objects:

• mailNickName starts with "SystemMailbox{"
  mailNickName starts with "CAS_"  AND mailNickName contains "{"
  sAMAccountName starts with "CAS_" ANDsAMAccountName has "}"
  sAMAccountName equals "SUPPORT_388945a0"
  sAMAccountName equals "MSOL_AD_Sync"
  sAMAccountName is not present
  isCriticalSystemObject = TRUE

Group size:

• Groups that have more than 15,000 members are also filtered out during the synchronization process to address performance concerns.