Wait, the resemblance thing is also used in other languages: "spitting image" in English, for example, and "copia sputata" in Italian. I'm actually wondering for the first time where it comes from, so maybe there's a reason for the Portuguese saying to be related to spit

Good points overall! I'd add that in my opinion "estaremos enviando" is closer to "we will be sending", which also better conveys the odd, misplaced telemarketer politeness vibes it carries.