Surprised this isn't at least account wide or maybe even global for all users? Are there really email services that bounce (not send to spam, but bounce) email based on domain? (Assuming you have SPF and DKIM and reverse DNS and whatever else configured correctly, which I assume you must to be able to use Mailjet?)
Yes, your domain can end up on a blacklist such as SORBS or Spamhaus and then you will have deliverability issues across the board. I have also heard from many companies and individuals with personal domains that have difficulty with Gmail and the verizon/aol/yahoo postmaster. They will just bounce you out of the blue.
DMARC and friends only help with authenticity. There's plenty of fraudsters sending authentic spam out there. The cost of a new domain is like $6, and there's plenty of people inputting their credentials on fake webmail signin pages for spammers that have trouble maintaining a credit card.
This is all true, but I don't understand why email providers will bounce personal domains. If you run DMARC and your domain is years old, what's the issue? I imagine that reduces the risk of spam by a lot.
I don't know why they don't just keep a master list of every bounced email across every domain (or maybe that's what their paid verification product is and I just haven't looked at it closely enough?) and let me set a flag when sending an email to reject anything they know is going to bounce.