Thunderbird has better buttons, they are larger and in the mail message.

Mail
1

Buttons

2

+++1

I would appreciate this as well: more and bigger buttons, configurable toolbars.

Thanks

3

I am a programmer and I know that’s easy job

4

Me, too for a long time now - if you have got the right library  it would be a fairly easy job and a well known standard feature of Windows applications nowadays.

5

Thank you for your suggestion, we’re currently working on a new UI for an upcoming release of eM Client, you can check out the preview on our facebook page.

Regards,
Paul.