Issue with html emails sent to non-microsoft hosted email addresses after upgrade to exim-4.98.2

Hello everyone.

I recently upgraded Exim to 4.98.2 from exim-4.95 and I've had reports of issues
with html emails arriving in 'chinese'' - see the screenshot on the right hand side when sent
to other than londonmet.ac.uk. londonmet.ac.uk addresses are  handled / hosted on M365
and the emails display correctly (left hand screenshot)

When we reverted back to exim-4.95.2 this issue went away, ie the same email (same contents) displaying correctly/as expected.

I'd be grateful for any pointers to any changes / factors I should have taken into account when building / installing exim-4.98.2

Many thanks,

Kind Regards,
Alex

Alex Tarry  ITS | Storage and Platforms Engineer | T5-20 | 020 7133 4498
London Metropolitan University is a limited company registered in England and Wales with registered number 974438 and VAT registered number GB 447 2190 51. Our registered office is at 166-220 Holloway Road, London N7 8DB. London Metropolitan University is an exempt charity under the Charities Act 2011. Its registration number with HMRC is X688.