I was able to confirm with the product team; HTML elements like anchor tags, header tags, and line breaks are supported in the note body. Anything more sophisticated than that (even if it works) is unsupported, and is subject to change without notice. In general, if you need more complex formatting you would likely be better served using the Timeline API.
Hi Derek - I wanted to check in on this again. I'm using a zapier integration to create engagements and using <b/> isn't working for that. Is there a new way of forcing a newline into the created Engagement (note)
Kevchen, to be clear it's: <br/> (short for break) not <b/> (legacy bold tag)
One thing you could do is use the Engagements API and see what value is actually making its way into HubSpot's database in case Zapier is doing something clever like stripping HTML from you (although I've seen that use case work as expected in the past)
Either </br. or <br/> appear to function as a line break, based on my testing. Additionally, it appears that some light HTML markup is supported in NOTE engagements, but I’m not yet sure if that’s intentional or not. I wouldn’t recommend using HTML in NOTE engagements since it’s undocumented and may be subject to change. I’ll touch base with the product team on that.