Table 3.

Corresponding author e-mail stability correlates with the number of sub-domains within the address

E-mail account status	Number of sub-domains
	0*	1	2	3	4	5+
Total	505	87,132	103,080	35,884	5,271	187
OK	–	61,719	61,167	16,280	1,710	36
Invalid account (but domain OK)	505	20,029	24,049	8,134	1,038	46
Domain failure	–	5,384	17,864	11,470	2,523	105
Communication failure	–	7,134	9,132	5,957	747	14
Invalid (but domain OK) (%)	100	23	23	23	20	25
Bad due to domain failure (%)	0	6	17	32	48	56
Communication problems (%)	0	8	9	17	14	7

^*E-mails without a top-level domain are always invalid.