What about using a Gantt bar? You could create a calculated field that is Date Mailed + 2 Days for the minimum estimated arrival and then another that simply hard-coded the maximum number of days after that. I think you could get a very nice looking visualization by adjusting the transparency of the Gantt bars.
Do you happen to have a packaged workbook with sample data in the same format as the data you are using? That would help with specifics for your situation.