I post all updates for my grid expeditions on my Twitter account @w5pfg. Generally I will post the pass date and time in UTC, the satellite name, and the grid from which I’ll operate. I try to do this in advance of a grid op as much as possible.
Twitter is probably the most versatile tool for notifying individuals about grid operations.
You can access my Twitter feed by web at: http://www.twitter.com/w5pfg
If you create an account on Twitter, you can configure email and text (SMS) alerts.
It is not necessary to have Internet access to send notifications. I can post a Tweet simply by sending a text (SMS) to a special phone number. Alternatively, I can send a Tweet even if I don’t have cell coverage but do have Internet access. To do this, you will need to have Twitter validate your mobile phone number with your account. It is painless.
Twitter provides a lot of flexibility. There is no cost for this service and it is generally as reliable or better than email service. It does not rely on an individual relaying information for you.