Each little stanza of this poem is like a sweet and juicy plum popped into the mouth. Read the poem aloud and try to taste the plums as you do. See, that's just the thing: this poem isn't about sound. It's about flavor.
We might encounter this poem as a note on the fridge and chuckle to ourselves at the disproportionate guilt the writer felt. Or we might hear it read aloud and imagine just how juicy, sweet, and cold those plums are. Whatever the case, we're not looking for rhymes or rhythm. We're looking for an experience, and that's just what we get.
In fact, the poem sounds like something anyone could say, any day. It reminds us that mundane experiences, like pilfering plums from your leading lady, can be a delightful experience, worthy of poetry. This, we think, is part of the point of this poem—it sounds simple and everyday, but it tastes delicious.
We will make one teeny tiny note on sound in "This Is Just To Say," though. This poem uses a little thing we like to call sibilance. Did you notice all those S sounds hissing their way through the poem? That's sibilance, and it creates a unique, subtle effect in "This Is Just To Say" (hmm, that title is pretty sibilant, too, huh?). All those S's slow the poem down, so that it hisses in our ears, like a hot, sweltering morning. A morning perfect for pilfering plums.