We've received some reports that users are unable to report harassing DMs they've received, and have confirmed that there does appear to be a bug in the official Reddit app that completely hides all reporting options in many cases.

Please make sure you report harassing or abusive messages to us, so we can look into and resolve these issues in our community. You can message the mods via the reporting options in the sidebar and main menu. Please include at least the name of the user to report, and, if possible, a screenshot of the message. Reporting harassment helps out everyone by ensuring we can remove abusive users from the community.

If you have access to Reddit on a computer, these otherwise-unreportable messages can be reported by logging into your account on Reddit.com. This probably works on a mobile browser too, but we haven't tested that. It also doesn't affect users of 3rd-party apps. We still recommend you report harassment by messaging the mods, even if you've already reported it using the report button; unlike reported posts, reported DMs (and chats) go into an automated system that does not guarantee your report will ever be read by a real human. Important— If you receive a message from that automated system saying a message you reported "doesn't violate the Content Policy", please make sure you follow up by messaging us, so we can ensure it does get looked into!

The bug appears to only affect Direct Messages messages (DMs), not Chat messages; another potential work-around, for users who only use chat, would be to turn off the DM messaging option for your account. This would prevent you from receiving any un-reportable messages, but would also prevent users who don't have access to chat from messaging you other than in comments. Some users have also stated that turning off both DMs and chat and requiring users to reach out via comments only had greatly reduced the amount of abuse they received, though again, it may reduce the overall number of people who will respond.

Messaging preferences can be adjusted on the official app under Settings > Account settings > Chat and messaging permissions. You can set separate options for Chat and DMs, based on your personal preferences.