تَأَخَّرَ الْبَرِيدُ. انْقَطَعَ الطَّرِيقُ بِسَبَبِ الْمَطَرِ.
The mail was delayed. The road was blocked because of rain.
The first report invites the implied question, Why was it delayed? The second explains that delay and consequently offers a strong case of explanatory resumption. It is not simple emphasis: a blocked road gives a causal circumstance, not a synonym for lateness.
If the first clause had itself asserted that the road was blocked, a following near-equivalent assertion would require a fresh evaluation. Rhetorical classification depends on the semantic relationship between the two propositions, not on a fixed list of surface words.