what does null mean after email address

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
what does null mean after email address	1.24	0.1	1492	72	39
what	1.2	1	2998	57	4
does	1.34	0.1	7313	77	4
null	0.68	0.5	6672	71	4
mean	0.1	0.7	8014	84	4
after	0.23	0.1	8378	80	5
email	1.78	0.6	5670	11	5
address	1.9	0.4	3866	31	7

Keyword	CPC	PCC	Volume	Score
what does null mean after email address	0.66	0.9	3787	41
what does null null mean on email	0.46	0.4	4450	75
what does null email mean	1.84	0.1	9927	4
why does my email say null null	0.32	0.1	368	14
what does null mean in an address	1.71	1	3325	68
why does my email say null	0.06	0.7	8589	4
email sender address null	0.03	0.6	6993	25
what does null sent a message mean	0.29	0.6	1559	21
outlook email shows as null null	0.93	0.4	3144	1
what does null mean after a name	0.67	0.5	3493	59
my yahoo email says null null	1.85	0.4	2221	28
what does null mean in text	0.87	0.6	98	6
null null yahoo mail	0.58	0.8	37	5
error code null mail.com	1.42	0.1	6585	61
null meaning in text	1.15	0.6	1514	55