1. No need for the tick on the icon, when the contact is already saved by the user
=> please remove this tick. You may keep it or not for unsaved contacts (curious to propose to save spam addresses with this + sign).
2. The green lock should be bottom-aligned with the line.
=> should be moved slightly up in the attached screenshot
Is the date field the right place where to display the lock?
3. The grey separation line is thick
=> please make it lighter or thinner
4. The "Me" ("Vous" in French in the screenshot) could be in plain text (no need to display it in BOLD). No need to keep the "Me" AND black brackets AND the bold characters, you may remove 2 of them. Keeping "Me" is enough with plain characters and without brackets.
5. Try to indent the To: Cc: fields, so that the addresses appear aligned with the date. Keep "To:" where it is currently and indent the addresses. Probably with indentation, there will be no need for the grey horizontal line.
6. Is there a technical need to underline addresses? The teal colour already highlights the address, you may remove the line under it.
1. I like to see the "tick" in the sender's icon, if the sender is already saved in my contacts.
2. I second this suggestion
3. I don't care, but @Paris Geek seems to have eagle eyes. So, maybe a fine tuning could be necessary...
4. I prefer to leave the "
Me" in bold.
However, what's the reason to show the own (recipient) address in (brackets)
The brackets should be removed.
Underlining the address is fine.
5. I second this suggestion. But please keep the gray horizontal separator (With adaptation according to No. 3)
6. Underlining the addresses should be fine, because this mark is common for "hyperlinks".
In conclusion:
I like the header's new design