I'll tag it as 由 alone. Kojien doesn't indicate restrictions, but it rarely ever does.

@@ -29,0 +29,1 @@
+<stagk>由</stagk>

由[...]4. 伝え聞いた事情。間接的に聞き知ったこと。「御病気の由承りました」
http://dictionary.goo.ne.jp/leaf/jn2/227493/m1u/由/
.
野沢先生は来年一年ドイツにいらっしゃる由、伺っております。
I've been informed that next year Professor Nozawa is going to Germany for a year.
[...]
"Yoshi is used to mark the content of what the writer has learned. Verbs [such as the 伺っております in the example 
quoted above] are often omitted, in which case yoshi also indicates the idea of 'I hear; it is said' etc."
"A Dictionary of Advanced Japanese Grammar" @由 (p. 738)

Perhaps 因；縁 can't be used for sense #2.

@@ -28,0 +28,6 @@
+<sense>
+<pos>&n;</pos>
+<gloss>piece of information that one has heard</gloss>
+<gloss>I hear that ...</gloss>
+<gloss>it is said that ...</gloss>
+</sense>

Koj (has both 因 and 縁)

@@ -12,0 +12,3 @@
+</k_ele>
+<k_ele>
+<keb>縁</keb>

daijs

@@ -9,0 +9,3 @@
+</k_ele>
+<k_ele>
+<keb>因</keb>