It's definitely a problem I've run into on both the sending and receiving side, despite being very familiar with it. I can't say that I know any universal solut

It's definitely a problem I've run into on both the sending and receiving side, despite being very familiar with it. I can't say that I know any universal solutions, but I've found it effective to essentially acknowledge it up front when first communicating with someone (e.g. a new member joining the team); despite working remotely, I always try to hop on a voice call with new teammates the first time I ever help them with anything so that I can better convey that I genuinely do want them to feel comfortable reaching out to me and that I will never be unhappy with them reaching out to ask something, even if it turns out that I might not be able to for some reason. At least for people I need to communicate with on an ongoing basis, being able to make a clear first impression can help mitigate any potential misunderstandings later on. In the absence of being able to do a voice call for an initial impression (e.g. if someone needs immediate help and I'm not available to do a call, or if it's someone I don't expect to need to talk to again in the future), the best strategy I've found is to directly state my good intentions. When I've had one-off discussions with support engineers at my current job to try to help them figure out a customer issue, I often start off by saying something like "I definitely can help you with this issue! If I'm slow to respond or accidentally miss some piece of information, it's totally fine to ping me again as much as needed; I might have to temporarily stop focusing on helping you to deal with other stuff that comes my way, but if I haven't said otherwise, you can assume that any prolonged radio silence on my end is from me forgetting rather than not wanting to help still :)". Even though this doesn't specifically address the idea of messages sounding more stern than intended, my experience is that being able to assure someone of good faith in general will help prevent any misunderstandings later on, regardless of the specific circumstances.