Exchange messages can't deliver after multi-replied

Question

Hi everybody,

Some users of our business departments need to reply emails with embeded images and attachments as their daily work progress reports to the managers. But those emails usually get bounced by Exchange server after a dozen times replies. The whole email conversation hasn't reached the message size limitation.

Currently the workaround I told the users is to create a new message and attach the email contained long conversations as attachment. But it won't always work when the attachment is .msg file, sometimes I have to compress the .msg file to .zip file to make the delivery work.

So may I know why the email can't deliver? And is there any way to avoid or solve this issue?