This means that I could be away from the office for several days and miss a message entirely, because it would have expired and disappeared by the time I returned.
1	This	this	PRON	DT	Number=Sing|PronType=Dem	2	nsubj	2:nsubj	_
2	means	mean	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	0:root	_
3	that	that	SCONJ	IN	_	7	mark	7:mark	_
4	I	I	PRON	PRP	Case=Nom|Number=Sing|Person=1|PronType=Prs	7	nsubj	7:nsubj|15:nsubj	_
5	could	could	AUX	MD	VerbForm=Fin	7	aux	7:aux	_
6	be	be	AUX	VB	VerbForm=Inf	7	cop	7:cop	_
7	away	away	ADV	RB	_	2	ccomp	2:ccomp	_
8	from	from	ADP	IN	_	10	case	10:case	_
9	the	the	DET	DT	Definite=Def|PronType=Art	10	det	10:det	_
10	office	office	NOUN	NN	Number=Sing	7	obl	7:obl:from	_
11	for	for	ADP	IN	_	13	case	13:case	_
12	several	several	ADJ	JJ	Degree=Pos	13	amod	13:amod	_
13	days	day	NOUN	NNS	Number=Plur	7	obl	7:obl:for	_
14	and	and	CCONJ	CC	_	15	cc	15:cc	_
15	miss	miss	VERB	VB	VerbForm=Inf	7	conj	2:ccomp|7:conj:and	_
16	a	a	DET	DT	Definite=Ind|PronType=Art	17	det	17:det	_
17	message	message	NOUN	NN	Number=Sing	15	obj	15:obj	_
18	entirely	entirely	ADV	RB	_	15	advmod	15:advmod	SpaceAfter=No
19	,	,	PUNCT	,	_	15	punct	15:punct	_
20	because	because	SCONJ	IN	_	24	mark	24:mark	_
21	it	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	24	nsubj	24:nsubj|26:nsubj	_
22	would	would	AUX	MD	VerbForm=Fin	24	aux	24:aux	_
23	have	have	AUX	VB	VerbForm=Inf	24	aux	24:aux	_
24	expired	expire	VERB	VBN	Tense=Past|VerbForm=Part	15	advcl	15:advcl:because	_
25	and	and	CCONJ	CC	_	26	cc	26:cc	_
26	disappeared	disappear	VERB	VBN	Tense=Past|VerbForm=Part	24	conj	15:advcl:because|24:conj:and	_
27	by	by	ADP	IN	_	29	case	29:case	_
28	the	the	DET	DT	Definite=Def|PronType=Art	29	det	29:det	_
29	time	time	NOUN	NN	Number=Sing	24	obl	24:obl:by	_
30	I	I	PRON	PRP	Case=Nom|Number=Sing|Person=1|PronType=Prs	31	nsubj	31:nsubj	_
31	returned	return	VERB	VBD	Mood=Ind|Number=Sing|Person=1|Tense=Past|VerbForm=Fin	29	acl:relcl	29:acl:relcl	SpaceAfter=No
32	.	.	PUNCT	.	_	2	punct	2:punct	_
