Inbox avoidance:  grossly delaying reading or replying to a specific message, while continuing to process messages received afterwards. 

Although the result is the same for the sender, avoidance differs from messages getting "buried" because the recipient is conciously aware that the message is waiting for a reply.

Causes

• Disinterest
• General TODO list management (low priority items linger)
• Bacn (mail you want, just not right now)
• Research needed / unsure how to respond
• Appropriate reply would take longer to compose than the average item in my email workflow

Effects

• Stress (some cogsci person could more acurately categorize what kind of stress)
• Avoidance of that person in other social situations

Management (this is my real-world management, NOT optimal)

• Tag as !DO in gmail
• Message sits in Inbox
• Message sits in Inbox
• Message sits in Inbox
• Message archived due to extreme irrelevance

Solutions

• For topics that frequently cause inbox avoidance, seriously reconsider my desire to be involved with that project.  Also see Zen Habits:  8 Great Anti-Hacks to Fundamentally Change Your Life
• Take control!  Promote how to best communicate with me via CommunicationProtocols.
• More research needed

References

@arielwaldman:  More and more true: if ur email isn't optimized to let me respond in 30 seconds, I probably won't answer it for a couple weeks.