Osewa ni narimasu?

Hi, I've recently came across this phrase and I've looked up the meaning on the internet (I sort of get the gist of it) but I'm not sure if this phrase can be use when receiving parcels from delivery guys?

I usually answer the door with just acknowledging my name when asked, so I want to know if "osewa ni narimasu" can be used instead to sound more polite?

"Osewa ni narimasu" contains various meaning.
eg, when you ask someone to do something for you, say "Osewa ni narimasu", in this case "thanks for doing it"
eg, when you are invited to someone's house for staying, say "Osewa ni narimasu", in this case "thank you for inviting me to stay"
eg, when you joined in a school class or work place and then introduce yourself, say "Osewa ni narimasu", in this case "thank you for introducing me to the class/work"

When you receive a parcel, just say "Arigatou gozaimasu", that sounds natural to me.

When delivery men/mover company staffs come and pick up your parcels/belongs(large number of quantities) and say "Osewa ni narimasu" as thank you for come and pick up those parcels/belongs to help me.

"Osewa ni narimasu" is not appropriate when receiving delivery. If you're using "osewa", you'd want to say "osewa-sama" instead in this case. They are two different things.

"Sewa" means "care-taking" and "o-sewa ni nari-masu" means that you are going to be taken care of from now on including the near future. As you can see, all of Tokyo Friend 48's examples are meant to be used toward people who are going to be related to you from now on. But once you have received the delivery, the delivery man's job is done. He is not going to take care of you any more.

Meanwhile, there also is the phrase "o-sewa ni nari-mashita". This means that you are thanking the person for having taken care of you up to now. For example, when leaving a hotel you stayed the night before, you can say "osewa ni narimashita".

I guess the word "osewa-sama" comes from "osewa ni narimashita", but since the latter sounds a little bit too formal to be used to a delivery guy, people use "osewa-sama" instead. You can also use "osewa-sama" to shopkeepers when you leave the shop.

I know that some posters on this forum do not prefer to use the phrase "osewa-sama" in the first place, but I brought it up simply because "osewa..." is the topic.

It is very interesting talk.

I suppose it depends on the mind of the person who accept the service whether the person say the phrase to the delivery person or not.

My mother said "Osewa ni Narimasu", as the same delivery person came to the house with the mind of thanks.
She said so, I suppose, she wanted to say that,
" I appreciate that you take care of me every times".

I used to say "Osewa ni Narimashita", when I leave taxi.
I use the past mode, it is because my mind mind is like,
"I appreciate that you took care of me to move".

I suppose that it should be no problem if you feel thanks to that person.

Thank you for the explanation, everyone. Appreciate it. :)

Say "go kuro san" meaning "thank you for the trouble (of delivering)".

"Gokuro san" is not incorrect but "gokuro sama" would be better if you want to be polite.