Has Hotmail blacklisted SendGrid?

[ClubCuddly]

Hi everyone,

After recently transferring my email delivery system to SendGrid, I've been able to get reports on what email addresses are invalid, and which emails are bouncing back to me.

While it comes in very handy, I have noticed that hotmail has blocked receiving of emails from SendGrid.

I haven't as yet tested to see whether this is an actual thing, or if it is just blocking things because the addresses don't exist, but I'm curious as to whether anyone else has had issues similar to this.