Symptoms
In Microsoft Exchange Server 2019 and Exchange Server 2016, when you try to sync a draft email message to the Mail app on your iPhone, you receive the following report that is generated by Exchange ActiveSync (EAS):
Synchronization with your iPhone failed for 1 items.
This issue occurs if a display name in the draft message does not contain a letter or number.
Resolution
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 6 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019. For Exchange Server 2016, install the Cumulative Update 17 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Third-party information disclaimer
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.References
Learn about the terminology that Microsoft uses to describe software updates.