Body of text overlapping in email reply to customers

[RayCad]

I've been made aware by a handful of customers that my reply email to their enquiry shows up as the text being overlapped and unreadable.

I use outlook to reply and it seems to be customers that are viewing via apple devices.

Wondering if anyone as any insight as to why this might be? I've only been aware of it happening for a couple of weeks.

[AlaskaGlacial]

I don't have a solution, but have been experiencing this same problem for over a year.