A quick test…

Hey

I just downloaded your plugin and am doing a quick test (which turned out to take a while).

The UI looks good.
Emails – a dummy button that goes nowhere. It would better to remove the Emails button beside the Newsletters, Templates etc menu bar.

Newsletters. (Brings an association with the post/pages screen).
Adding a quick edit when hovering over the title of the newsletter would be good to include delete, duplicate and whatever else.
Instead of View – what about adding a thumbnail screenshot of the newsletter. Moving View directly to the Edit Email Content.

Edit Email Content
What about a preview button to the right of the Cancel button?

Subject and Main Content looks nice and clean.

Template side area.
Here you can show a thumbnail of the various Templates. So the user can click the thumbnail (think activating a theme) to select the template they like.

Templates.
What about a thumbnail showing what each looks like?
What about Edited date beside the name and future thumbnail?
Perhaps removing OR adding a quick edit menu here as well.

Clicking Clone or perhaps Edit.
Leads to a screen asking for Template Name. Then a Save & Next.
It would be better to have just one screen. Template name and then right below template with side area Page, Content Header etc.
Buttons have an X and a Disc. I have not seen these used before now. Remove the icons and get the text back keeping consistency.
I really like the customization of Page, Content Header, Content and Content Footer.

Custom Templates (menu item could have a title that shows up on hover that says requires Pro version)
Seems fine.

Social Icons – Could be draggable. Start with the most popular. Then go into alphabetical order. The user could drag the social icons in the order they want them to show in the e-mail.

Going back into Edit Email Content.
I miss having a way to easily add the social icons where I want them. Be it at the top or bottom of the e-mail.

As you noticed I see a lot of areas that could be nice to improve.
I can work with you guys on creating additional feedback to your plugin free version and pro. Let me know.

I run the web site: http://easywebdesigntutorials.com/

https://ww.wp.xz.cn/plugins/sendpress/