Showing an email

I received an email on my phone and replied to the email on the phone.
I moved the reply to a folder.
When I viewed my email in eM Client the reply was in the folder but I could not find the original email. Not in trash and not in inbox.
I noticed a link at the top of the reply email “Show 1 older email”. When I clicked on the button the original email appeared.
Why?
How can I ensure that all emails are shown?
Thanks

This is because the messages are grouped in conversations. When you see older email listed above, you can scroll up to see them. Each message will be collapsed, but click on the one you want to see and it will expand.

If you don’t want to use conversations, you can disable them by selecting Menu > View > Conversations > Disable Conversations.