The Analytics dashboard is not showing correct data?
In order for the data to be collected and displayed on the dashboard, your emails need to be routed through Exclaimer servers.

See Engagement Analytics and Signature Usage Analytics.
Why can't I see a specific group (group implies members from the Microsoft 365/Azure AD or G Suite/Google directory) when defining which groups will be included to use the selected signature?

Only the group's contact details synced with Exclaimer are available for you to select from. 

Please have a look at Signature Senders for more information on how to define specific senders (which includes groups, email addresses or domains) from within your organization who will be included in using the selected signature.

Does Exclaimer work with groups that are hidden from the Global Address List?
Yes, groups that are hidden from the Global Address list are still synchronized by Exclaimer and can be selected as a condition when configuring signatures.
Can the ExclaimerReadOnlyPowershell account be deleted?

Yes, you can safely delete the account.

The ExclaimerReadOnlyPowershell account was previously necessary for synchronizing custom attributes; however, following some enhancements made by Microsoft, this feature has been upgraded so that this account is no longer necessary. 

Where is that information stored if the details uploaded via the User Details Editor do not update the Azure AD?
All data uploaded to the User Details Editor feature via the CSV Upload option or other user options are stored in Exclaimer's own load-balanced data centers.
Are user photos embedded or web-hosted?
All user photos uploaded into our system will be embedded into the message when the signature is applied. 
Can I upload images for multiple users at once?
Yes, of course! For more information, please see how you can upload multiple user photos at once.
What happens if the user photo field is defined in the signature, but no image has been uploaded?
By default, the User Photo element is hidden in the signature for users who do not have an uploaded photo.