Frequently Asked Questions (FAQ) 

See chapter Configuration.

See chapter Where to get help.

This was a known issue that has been fixed in the related dependency oliverkroener/ok-typo3-helper (version 3.1.2 and later).

Emails with inline images reference the embedded attachment through a cid: URL in the HTML body. Microsoft Graph does not auto-generate a matching Content-ID for inline attachments, so the reference was left dangling and the image rendered broken in the recipient's mail client. MSGraphMailApiService now carries the original Content-ID over to the Graph FileAttachment, so inline images display correctly.

No change is required in this extension — simply make sure oliverkroener/ok-typo3-helper is on version 3.1.2 or newer (composer update oliverkroener/ok-typo3-helper). The dependency constraint (^3) already allows it.