I find that in email notifications, the hyphen/dash is being escaped into the character string &#8211 (em-dash) when it occurs in topic titles, forum titles and user display names. I have not tested forum names.

For a topic with the title as on the following line:
Hyphen – endash – emdash — nonbr hyphen ‑ figure dash ‒
all these characters survive except for the first hyphen/minus sign. If this same sequence is included in the body of a topic, it is delivered OK, so this is NOT a WP server or email issue. This does not occur in notifications for a WP post, so I believe it is a bbPress issue.

I have tested this under WP v5.0.3 and with bbPress v2.5.14 the only active plugin and with the theme Twenty Nineteen.

[@stuartataltitude Participant 5 years, 5 months ago]

I have the same problem on my site. It is common for forum post titles to contain a hyphen but the – makes the notification email look very unprofessional. Would be great if this bug could be fixed.

[@stuartataltitude Participant 5 years, 5 months ago]

‘but the -‘ should have read ‘but the #8211’