Xobni used to integrate with Outlook/Gmail that scanned your e-mails and gave you a sidebar with Contact photo, e-mail, phone #s, social profiles, show your e-mails with them, show attachments exchanged...Yahoo bought it and promptly killed it years ago...is there any add-on or just e-mail client that is like that these days? I miss it.
Oh my gosh! That's certainly a blast from the past. Microsoft ended up buying it and they tried to integrate it into Outlook, but the future just disappeared for some reason.
It's like they used the advance indexing capabilities, but got rid of the user interface that could allow for brilliantly efficient searching.
Yeah, Mailspring is what I use currently, but the sidebar pretty much just shows the list of e-mails, no other data, but it is the best of what I've found on my own.