Before I moved into community full time, I was a project manager working on a lot of different things. As a project manager, you tend to have a large portion of your day tied up in difficult conversations, and what I learned through is: always deliver bad news over the phone. Deliver over the phone, follow up in an email, but give people space to be able to react in person or as near to in person as you can, and have that hard conversation together.
Since I started this practice, video conferencing has gotten a ton better, and that 'near enough' is sometimes good enough! (I have other thoughts on what to do in days of amazingly bad connections, which is more common than you might think these days!)
I think about the conversations that I didn't have over the phone and how they turned out and those end up being some of my bigger regrets. It's certainly more difficult than sending an email, because not only do you know that you're going to be disappointing someone else, it's hard to be able to tell people no!
On your own end, you have to practice being able to be the professional bearer of bad news, work through your own feelings about the conversation, and be graceful at the same time as you can hear the other person's disappointment in a professional way.
In community, this takes different forms. You don't always get the chance to be able to do this in person, because timezones, the community just doesn't work like that, or the difficult conversations are ones that you just don't know how to have. In fact, the worst ones for me are the conversations that I didn't even know were going to be difficult—the ones that catch you by surprise.
There's really nothing worse than minutes going by of 'X person is typing' and you know that they're both having trouble articulating what it is they want to say, and they're spending a ton of time trying to say it—and it could have been easily avoided by getting on a phone call. I'm not always sure of how to change that dynamic, because it always feels so much easier to just continue emailing back and forth until your inbox is full of disaster, but I do know that trying to have the conversation in real time is so much faster.