Programmatically adding Signatures to an email

I have used this code for several years when programmatically creating emails (ii Delphi).

On one machine Window 10/Microsoft 365 it started ti fail 1/3 weeks ago (not send the email).

MailItem: _MailItem; (from Outlook_TLB)

MailItem.GetInspector;
MailItem.HTMLBody := Body + MailItem.HTMLBody;

Error Message : Sorry, something went wrong. You may want to try again

This happens every time I create an email (not on my Windows t machine) Skipping yjis code sends the email (but no signature - which we need).

I reinstall 365 to no avail.

When I deleted the signature and ran the code it also errors (i.e. adding a null signature)

Any ideas about what has been corrupted would be appreciated.

TIA

Effy