It's working now, but i have 5 messages within a 30 minute window all with the same error and multiple other messages to the same address without any issue. Only link to 550 error is links to theDonald. Even message content (text) was the same except a hyperlink to thedonald.

If anyone can look at the error message and give me any insight, let me know.

Unless it's Outlook blocking it, work network hasn't changed. I'll try using webmail and report back.

I got it to work as "the donald dot win", but masking the link and even thedonal.win didn't work.

Will switch this afternoon.

I'm using Outlook to send out and haven't had any issue before. No changes to network structure in months.