This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.
If the date is April 26, it displays the message "─╩╣╙├╡─╩╟╡┴░╚φ╝■,╟δEmail To:firstname.lastname@example.org ╤░╟≤░∩╓", otherwise if the date is the 26th of any month, it displays the message "─╩╣╙├╡─╩╟╡┴░╚φ╝■". If the date is divisible by 5, it exits Windows.
Opening an infected spreadsheet will infect Excel's startup directory, and then infect other spreadsheets.