M365 Changelog: Outlook Mobile Now Supports Multiple S/MIME Certificates

MC411680 – Outlook mobile (iOS and Android) will allow users to manually select their S/MIME signing /encryption certificates if there is more than one valid certificate available, and set them as active for signing and encryption. 

When this will happen:

GA: Rollout will begin in late July and is expected to be completed by end of August.

Government Clouds: Rollout will begin in late August and is expected to be completed by mid-September.

How this will affect your organization:

If your company does not support S/MIME or does not need multiple S/MIME certificates, this will have no impact on you. If your company wants to use this feature, you will need to go on Intune and disable your SMTP address check for SMIME. Users will then be able to view multiple SMIME certificates and select them for signing and encryption. 

What you need to do to prepare:

There is no action needed from you at this time if you do not need to use this feature. If this feature is needed, you can follow additional instructions in this link for setup. Additional information