Another thing to consider is that these messages will be set to expire and disappear within a set period of time, meaning users cannot retrieve them and read them later (as they can with e-mail).
1	Another	another	DET	DT	_	2	det	2:det	_
2	thing	thing	NOUN	NN	Number=Sing	11	nsubj:outer	11:nsubj:outer	_
3	to	to	PART	TO	_	4	mark	4:mark	_
4	consider	consider	VERB	VB	VerbForm=Inf	2	acl	2:acl:to	_
5	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	11	cop	11:cop	_
6	that	that	SCONJ	IN	_	11	mark	11:mark	_
7	these	this	DET	DT	Number=Plur|PronType=Dem	8	det	8:det	_
8	messages	message	NOUN	NNS	Number=Plur	11	nsubj	11:nsubj|13:nsubj:xsubj|15:nsubj:xsubj	_
9	will	will	AUX	MD	VerbForm=Fin	11	aux	11:aux	_
10	be	be	AUX	VB	VerbForm=Inf	11	cop	11:cop	_
11	set	set	ADJ	JJ	Degree=Pos	0	root	0:root	_
12	to	to	PART	TO	_	13	mark	13:mark	_
13	expire	expire	VERB	VB	VerbForm=Inf	11	xcomp	11:xcomp	_
14	and	and	CCONJ	CC	_	15	cc	15:cc	_
15	disappear	disappear	VERB	VB	VerbForm=Inf	13	conj	11:xcomp|13:conj:and	_
16	within	within	ADP	IN	_	19	case	19:case	_
17	a	a	DET	DT	Definite=Ind|PronType=Art	19	det	19:det	_
18	set	set	VERB	VBN	Tense=Past|VerbForm=Part	19	amod	19:amod	_
19	period	period	NOUN	NN	Number=Sing	13	obl	13:obl:within	_
20	of	of	ADP	IN	_	21	case	21:case	_
21	time	time	NOUN	NN	Number=Sing	19	nmod	19:nmod:of	SpaceAfter=No
22	,	,	PUNCT	,	_	11	punct	11:punct	_
23	meaning	mean	VERB	VBG	VerbForm=Ger	11	parataxis	11:parataxis	_
24	users	user	NOUN	NNS	Number=Plur	27	nsubj	27:nsubj|30:nsubj	_
25-26	cannot	_	_	_	_	_	_	_	_
25	can	can	AUX	MD	VerbForm=Fin	27	aux	27:aux	_
26	not	not	PART	RB	_	27	advmod	27:advmod	_
27	retrieve	retrieve	VERB	VB	VerbForm=Inf	23	ccomp	23:ccomp	_
28	them	they	PRON	PRP	Case=Acc|Number=Plur|Person=3|PronType=Prs	27	obj	27:obj	_
29	and	and	CCONJ	CC	_	30	cc	30:cc	_
30	read	read	VERB	VB	VerbForm=Inf	27	conj	23:ccomp|27:conj:and	_
31	them	they	PRON	PRP	Case=Acc|Number=Plur|Person=3|PronType=Prs	30	obj	30:obj	_
32	later	late	ADV	RBR	Degree=Cmp	30	advmod	30:advmod	_
33	(	(	PUNCT	-LRB-	_	36	punct	36:punct	SpaceAfter=No
34	as	as	SCONJ	IN	_	36	mark	36:mark	_
35	they	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	36	nsubj	36:nsubj	_
36	can	can	AUX	MD	VerbForm=Fin	30	advcl	30:advcl:as	_
37	with	with	ADP	IN	_	38	case	38:case	_
38	e-mail	e-mail	NOUN	NN	Number=Sing	36	obl	36:obl:with	SpaceAfter=No
39	)	)	PUNCT	-RRB-	_	36	punct	36:punct	SpaceAfter=No
40	.	.	PUNCT	.	_	11	punct	11:punct	_
