Overview:
The Send email button is not visible for a few user profiles on the Account detail page in CRM Offline. It is visible Online.
Root Cause:
It is usually due to the user profile not having Create and Edit permission on the Sent_Email_vod object.
One more possible reason is that there is no active VMOC for the Multichannel Consent object.
For Online use, the Sent Email related list and Send Email button must be on the Account detail page layout. Also, the user needs to Create access to the Sent_Email_vod object.
For Offline apps, the Send Email buttons are controlled by the user's object access. The Send Email appears if the user has Create, Read, Edit (CRU) access to the Sent_Email_vod object.
Solution:
Set Create, Read, Edit access permission for the user profile.
Create an active VMOC record for the Multichannel Consent object if there is no active VMOC for the Multichannel Consent object.
Related Documentation:
Veeva CRM Help: