I tend to ignore people who just say hello - unless it's someone I'm closely working with on a project. I intend to get back to them, but, because I don't know what they need I can't really prioritize it so I subconsciously prioritize last (I don't intentionally mean to) and since I have so much to do I usually never get back with them until: they provide context.
Much better is something like hello, don't mean to bother you but hey when you have the time can you <whatever>. That works so much better - many times I'll just take care of it immediately just to keep my backlog of work from growing. If it's something that's going to be more involved I'll let them know that and work out when they're needing it done by. Then I'll get it on my to-do list.
If it's urgent then say so - hello, sorry to bother you but this came up unexpectedly and you're the only one that can do <whatever>. Can you help us out? I may be annoyed, but I'm not going to shoot the messenger.
Much better is something like hello, don't mean to bother you but hey when you have the time can you <whatever>. That works so much better - many times I'll just take care of it immediately just to keep my backlog of work from growing. If it's something that's going to be more involved I'll let them know that and work out when they're needing it done by. Then I'll get it on my to-do list.
If it's urgent then say so - hello, sorry to bother you but this came up unexpectedly and you're the only one that can do <whatever>. Can you help us out? I may be annoyed, but I'm not going to shoot the messenger.
Just hello? No. It slips off my radar.