I'm supposed to give a presentation at an academic conference in the coming days but have fallen ill. What is the best way to send my regrets? Should I also send a doctor's note? It doesn't provide details of my condition but does have other personal information such as date of birth and home address. I just wonder if any of this is the conference organiser's business. At the same time, sending an email without proof that I am truly incapacitated doesn't seem like it's enough either. I'm still not sure what to do about the presentation I'd prepared - whether or not to send it anyway etc. I'm trying to focus on getting better, but I am worried that this medical issue will ruin my good name. Any advice would be appreciated.
Just tell the convener that you will be unable to present due to unforeseen circumstances. That is enough and will be understood — there can be many reasons and it won't be a first time. He/she will be glad that you inform him/her at all — it happens all to often that people simply don't turn up without giving any information at all. The convener shouldn't need a doctor's note.
That being said, is any co-author travelling to the conference, or perhaps a colleague familiar with your work? If yes, you could ask one of them if they are willing to take over your presentation. I've done this for colleagues and although I wasn't able to answer detailed questions from the audience, it's still beneficial both for me (visibility to experts in the field) and to the first author.
Just inform the organisers as soon as possible, they might want to rearrange the programme accordingly, and therefore might to contact other authors to see if they agree to change their scheduled slot. You don't have to provide proof, as gerrit says, things like that happens quite often.
In addition to gerrit's suggestion to see if a colleague could present your talk, you could also check with the organisers if you can present your work remotely (if your illness allows for it). I attended a conference recently where one author presented his slides through a Skype conversation, and another talk was presented as a video, while the author was available in the end for any question. Although it's not ideal, it's still better than not presenting your work at all.