I only posted this yesterday (the 8th), but I've already changed my tune in the 24 hours since, so I've reworded it rather than add an update to the existing article. My stance now is; unless you absolutely need to use it for some strange reason, just get rid of Outlook. It's clearly a big pile of shit and there are better alternatives on Android.
I downloaded Outlook onto my Android device because I wanted to connect to my obscure and basic email account via IMAP as well as eventually my old Hotmail account, so I just assumed Outlook would be OK despite there being a plethora of other apps I could use and that I've never been fond of Outlook in any of it's incarnations over the years anyway.
After I set it up it worked fine, until recently that is when I noticed in the Direct Share section of the share panel on Android that a bunch of contacts from emails I'd received had shown up. These 'phantom' contacts also showed up when I tapped the magnifying glass icon as if to search for a contact, but I couldn't remove them as it only gives you the option to create an actual contact from them, indicating they were some kind of suggestion from the app.
Keep in mind at this point I had not added any other accounts to the app yet (even though I intended to) and my IMAP account is so basic it lacks any kind of suggested contact functionality; in other words this was all Outlook's doing. It's also not the first time Outlook had borked up on me as not long ago it managed to alter the email address login entirely by itself somehow, causing login failures of which it didn't tell me about. I only noticed the problem when I realised I hadn't received any emails for a week and opened the app to investigate.
The login issue was easily corrected but the only way I was able to get rid of the phantom contacts was to reset the app by clearing its cache and storage then setting it up again, which appeared to work until yesterday. I had finally got around to connecting my old Hotmail account (now of course a Microsoft account) to Outlook as well, which I did easily enough, only to find the exact same issue had sprung up with contact suggestions from the newly added account showing up in Android's Direct Share section. Once again tapping the magnifying glass icon as if to search for contacts immediately showed all these 'phantom' non-contacts just like before, still with no apparent way to delete them.
I eventually figured out that you can login to Outlook online and delete these suggestions by composing an email and then cycling through them by starting to type a letter in the 'To' email field. You evidently can't do this in the app though, since although suggestions do show up when you compose an email they can't be deleted.
Meanwhile I also found three settings for suggestions in the app and in the online version. In the app there's a setting for 'Quick suggestions' that can be turned off but only for the Hotmail account (the IMAP account didn't have the option at all). I'd already turned it off so clearly that didn't affect the app creating contact suggestions and I could find no option to prevent the app from pushing these suggestions to Direct Share, which it shouldn't be fucking doing at all anyway — I mean I could understand it pushing actual contacts to Direct Share but not suggested contacts, because some of these contacts were pulled from senders that I'd only received one email from. Hardly a reason to use that sender's email address as a suggested contact, is it Microsoft?
In the online version of Outlook's settings I did find three more options for suggestions, two once again for 'Quick Suggestions' that I turned off and a further one for 'Suggested replies' I also turned off. None of this seemed to actually impact the fact the Outlook app was showing these suggested contacts at all though and the only way I could get rid of them completely as stated above was to delete them when composing an email.
Then today rolls around and I noticed yet another weird addition to the Direct Share panel which yet again came from Outlook and my Hotmail account. Upon attempting to figure out where it had come from (as this one wasn't actually showing up as a suggested contact but instead seemed to be the contents of an email I'd sent at some point), I noticed once again it had pulled two addresses from two emails I'd received overnight from my IMAP account and started suggesting them as contacts as well. It was at this point, I lost my shit.
When app developers start fucking around with their apps to the point where this sort of rage-inducing calamity occurs, there's only one sane course of action as far as I'm concerned: Uninstall the bastard. So I did and I won't be using it in the future either which I suggest you don't either. I couldn't care less if this was a bug introduced by an update or if it's all intentional (but if it is intentional someone on the Outlook development team needs to have their head examined). From hence fourth I will instead use something else that isn't so ridiculous, something I should have done in the first place.