Could you go into more detail about your setup? Maybe in another post? A lot of readers here know or loathe the mail workflow within the terminal, details matter.
I’m not the author of the aritice, but I do read my mail via the shell. Or more specifically, mutt.
Anyway, my setup. Unix setup using Postfix. Upon local delivery, postfix will pipe the messasge through procmail, which does the filtering of messges for me. Yes, the syntax of procmail sucks but a) it’s there and b) it can do just about anything you want. I use basic filtering, whereby each email gets filed into a folder—for example, email from my SO goes into one folder, email for mailing list X goes into folder X, mailing list Y into a folder Y, email from my parents into another folder and so on. You can also have procmail pipe the mail into a program, so say, automated summaries of log files could be run through another program looking for problems and alert you someother way (email, or SMS, or whathave you). I don’t do this since I don’t get work emails to my private account , but it’s possible.
I have mutt configured to look for new mail in the folders. If I don’t have time for the mailing list stuff, I can easily skip that until I have time. Perhaps it’s just me, but I don’t need to “hide” email, or “delay” email for a day or whatnot. The only issues I have with this are:
clients that only send HTML email without a text-only alternative. It happens less than you would think, but when it does, I have to go through some additional steps to view the email (feed it to Lynx from within mutt).
attachments also require a bit more work, depending on what they are. PDFs or other files like that aren’t bad. Images are quite involved, but only because of my setup (I ssh into my email server  and run mutt there—any images I have to save, then download to view, but again, that’s because of how I set things up on my end; your milage may vary).
So that’s my setup. It’s nice because phishing emails are obvious, attachments aren’t auto-executed and HTML-only-no-text-alternative is almost always spam, and it’s fast to burn through a ton of email (since I check email on the server, I don’t have to download the mails to read them).
 I use a web interface for work email. It was either that, or use Lookout! Microsoft as an email client. I would love to use a shell to read work email but I haven’t looked into whether that is possible or not.
 I run my own email server, in addition to web server, DNS and gopher.
None of this is shell-specific other than the final paragraph on filtering, wherein the author tells us nothing other than “my system is great”.
I really want to move to mail in the terminal, like Mutt. But I can’t do that because my Inbox Zero workflow relies entirely on Google Inbox clustering mail for me, hiding anything that isn’t directly addressed to me until the next day, letting me snooze mail I can’t deal with yet… I wish there was a terminal equivalent! (whereby “wish” means “it would be rad but I don’t have the time to do it so don’t reply telling me to scratch my own itch ;) )
Depending on what you’re doing, scratching this itch shouldn’t actually be very hard. I have a very simple mail filter that just kicks anything not addressed to me personally into a folder called Triage that I go through once a day. Doesn’t break things down as far as Inbox, but gets me 99% of the way there. (I’ve also gradually added additional bucketing for travel and whatnot, but that’s been a slow burn.) If you want to use Mutt, something like this remind-based workflow would then cover your snoozing just fine.
It’s completely fine if that’s not enough; Inbox does a lot. But based on the two things you highlighted, you might be surprised how quick it is to get to 90%.
You definitely can manage something of the like easily with mblaze. I’m using it for email along with fzf, and it’s been fun so far. I have a few shell scripts to help with redundancy, and that kind of clustering is like two pipes away.
I frequently use and always love alpine, even on OSX via homebrew. It’s not as bare-metal as mutt or nmh, but it’s fast, easily configured, mailbox and attachment handling are good, find-by-select-filter inside mailboxes is really quick and responsive (with a decent IMAP server), and overall I just find it easy, distraction-free and very efficient.
I’d love to hear more details. I also use nmh, but I don’t have a filtering system I’m happy with.