In conventional email clients (Outlook, Thunderbird …) after sending a reply to the e-mail icon is displayed in ‘answered’ - we called it the figure below 
You can set the following display ‘answered’ response is sent’ in eM Client? I searched several settings and and found none 
I do not get the status whether he was e-mail was sent, and icons I do not see none at all the status - read / unread, and so on.
In conversation mode, this is not available by design, as all grouped conversation are combined into one line. However, the header of each emiall does indicate a response or forward. To get the functionality back you desire, go to menu/tools/settings/mail/read and either check “Disable conversations” or check “Show conversations in message detail only”.
as an additional question on this: would it be much development to make that reference of having replied to a mail, clickable to the original sent message? Often I need to lookup what I’ve replied to someone, and currently I have to search for that mail by looking up the date and time, but if you could simply click on that line that says ‘you’ve replied to this mail on … at…’ then that would save time!