Outgoing SMTP is not blocked and will function, but is frequently blacklisted by recipients who refuse to accept email originating from a residential IP block. I have a relay in Amazon-EC2 that sends the email. Some recipients continue to not like that, but doing SPF/DKIM/DMARC goes a long way, and I've had no trouble sending to recipients at gmail and at various MS outlook/o365ish recipients. The biggest issue I have is that if the cablemodem goes offline for a long enough time, my IP address changes. But I've got by now a well-established checklist of stuff that I need to do when the house IP changes, so I just walk through the list and all is well in a few minutes. Decent email senders will queue the bounced email for a few days before bouncing back to sender and I'm not aware of having lost anything. --MCV.
I think the answer is "it depends". As Mike Voorhis says, his home stuff just works. And I certainly allow incoming SSH and other traffic to my home network. I honestly haven't tested if they block outgoing SMTP (port 25 traffic) recently, but checking now, they don't seem to be blocking it since I could get to my VPS on port 25 from home no problem.