When I’m replying to existing emails, past emails are mentioned as expected in the content of the email sent in eM Client or over Outlook.
However, in Gmail, where the past email content should be collapsed by default, it isn’t - and all the content is being presented fully as part of my existing email content. See below an example.
Is that a known issue or it’s fixable with the existing configurations?
That’s correct. Gmail parses the content to find exactly the past email content (so it hides it - see below a screenshot), and it seems it can’t find that for emails sent through eM Client.