In my opinion it doesn’t. It’s a part of a greeting card, sent as a postcard, but in my eyes it is not a postcard.
I would rather receive the whole greeting card, but still here, I prefer postcards.(postcards, that are postcards originally, not a postcard size of part some other item.) But if someone would have a gorgeous wolverine greeting card, I’s rather have it as it is, not cut.
Not for everybody… For me, a postcard is a store-bought or free card (originally) purposed to be sent without an envelope.
Flyers, or cards which once were greeting cards or food packages aren’t real postcards and I’d only send them to users who state in their profile that they appreciate handmade / selfmade cards.
There are many users who buy their cards and have the expectation to receive store-bought ones too. I don’t want to send re-/upcycled greeting cards to people who aren’t happy with such cards. (But I’ve already sent some recycled food box cards to people who wanted to receive them.)
When a card format like recycled greeting cards evokes discussion, should I stick with the idea and send it out of principle, or should I reserve the idea for members who can appreciate it?
Isn’t Postcrossing about giving strangers little happy moments when they open their mailbox? I may be a people pleaser, but I don’t want to evoke raised eyebrows or a discussion about rules with my card. I intend to make people happy with what I send. 
And a normal / real postcards just has better chances to reach this goal.
Hey @Cassisia and @S_Tuulia thanks for sharing your thoughts. I understand that out of respect and courtesy for other people’s preferences, one would just go with whatever the other person wants as long as they’re happy because that’s the point of this hobby. I personally wouldn’t send someone a handmade one if they’re not into it
But I’m honestly still baffled when people are adamant that postcards must be bought. I’m really new to Postcrossing (I just discovered it this week, but I do love writing letters/greeting cards before this week and own an embarrassing amount of stickers and washi tape) so please forgive me if my questions sound basic.
a. Quality difference between greeting card and shop bought printing house manufactured postcard? Often yes, as the half of greeting card is usually empty (for me it’s quality to give credit to the artist and maybe see the copyright, the printing company (if I’d like to order there)). And often these are thinner as well, as they are meant to be the folded card, in an envelope.
b. I’d say here, common sense (used by one who is willing to use the language as the majority), should be enough. Of course, I would be happy to read for example a standard for postcard made by ISO, but it might be because I like standards in general.
As in word usage normally, it’s an agreement what word is used when we refer to a certain object. (Like postcard often is rectangular shaped piece of thin cardboard ment to send on it’s own. So, yes, postcard can be a piece of cardboard, but not all pieces of cardboard are postcards and postcards can be other than a rectangular piece of cardboard.)
In general people have the ability to recognize and categorize objects, so for most of us knowing this comes naturally out of life experience. They don’t have to intentionally start thinking every time, what is a postcard, or wonder, if they do this and that to some object, does it become a postcard.
Yes, size and thickness are important, in my opinion, just it’s not too easily lost or torn.
In handmade postcard the main thing is to make it so that it is expected to survive the mail. (I don’t count half a greeting card as handmade, because the one who cut it, didn’t make the card. So far no one has told the artist info either.)
Interesting question(for me) is: is it really hard for someone to tell what item is a postcard?
Or are people just trying to justify themselves, playing stupid, “not knowing”?
Still, my advise for anyone wondering is, send the whole greeting card, if it’s the perfect card for someone, and add a postcard with it, so you followed the rules (sent the postcard). But oh …I think, often the greeting card is used, so one must tear it, right 
and come up with explanation, it was so perfect topic… yes, I’m a little suspicious 
not towards anyone certain here now in this topic, but based on my experience.
Recently I got a “postcard” that to me looks clearly like cut out greeting card 
I wonder should I always tell something, so they don’t think I liked it. That seems too rude, so I don’t do it, but when I don’t say anything, then they get the false impression of “no one noticing”.
Good thing, seems to me, most who join this postcard exchange, are prepared to look for postcards to send 
I can understand this - I collect ad cards (which are given out for free) and there are great ones! But most members state in their profile that they don’t like them and only want to receive store-bought cards.
There can be a difference, in my opinion it’s at first about the thickness and quality of the paper. As @S_Tuulia wrote, half a greeting card usually isn’t as sturdy as a postcard. It’s a pity when a selfmade card arrives torn or wrinkled because the paper is too thin.
And it can be about print quality too - self-printed pictures sometimes don’t have the same quality like professionally printed ones.
(And, but that’s my.personal opinion: If I have the impression that someone has recycled a used (greeting) card or even a flyer without writing space just to save money, it leaves a strange feeling because I don’t to this and send real postcards. 
)
@sillyapplepie13579, your thoughts on this are really interesting! Let’s talk “postcard ethics”.
Postcrossing has defined in the FAQ in “What can I send?” what a postcard is:
It can be a postcard you bought in a store or a handmade postcard, as long as it hasn’t been previously used.
In this sense, a selfmade card - probably also a cut greeting card - can count as postcard by the rules. But in my experience, most users don’t appreciate these kind of cards, and some think that a cut greeting card isn’t a real postcard.
I’d make a difference between selfmade cards - such as cut food boxes.or half a greeting card - and handmade cards with an artistic background, where the sender has drawn / painted something.
A folded / greeting card must be sent in envelope. So no postcard at all. A piece of cardboard, cut greeting card can be mailed as postcard.
But, if one sends the greeting card and a postcard, it’s all ok. They can put the postcard and greeting card in the same envelope. Yes, postcards are meant to be mailed without an envelope, but it is not a requirement.
The only thing one has to send, is a postcard, but you are allowed to send also the greeting card, if it is pretty, perfect etc.
https://www.postcrossing.com/help/what-can-i-send-on-postcrossing
This can be also because they haven’t seen all kinds of ad cards. In the beginning, I thought ad cards are the ones that have the advertising also in the message side, so there is only room for address.
Like this is an ad card for a concert:
So, there is not much room to write the message, and I understand not all are interested in other countrie’s junk mail.
I agree, such cards aren’t great. But there are really funny, witty and cute ones! In Germany, there are “Edgar Freecards” ad cards, distributed in cafes, bars and restaurants. They are numbered, have a bit of a cult status and even are collection objects.
I’ve picked some good ones that I would love to receive from my ad card box - I’d never consider them as junk mail, as they don’t get stuffed in your mailbox but you decide to take them with you:
@Cassisia These ad cards are so gorgeous! Thanks so much for sharing this lovely photo, I didn’t know such pretty ad cards existed.
Also, thanks so much for responding to my message with your insights. Thanks for describing the quality difference and I agree that stating one’s preference as store bought is a good way for quality control, as it leaves a strange feeling to receive something someone improvised to save money when you don’t do the same. I also liked your distinction between self made and hand made, which requires a certain level of skill
I’m glad that you liked them too! If you like, I’ll send one to you. :
These are all really nice and to be honest…nicer than some ‘real’ postcards I’ve received! 
I’ve also just received some beautiful postcards from Etsy that have only the artists name on the back. There are no address lines, and no dividing line or postage stamp area marked. I’m now really worried about whether to use them or not. They are really beautiful cards. And were not cheap. But now I’m worried someone is going to get upset and think I’ve cut up a card to send. I didn’t realise this was going to be so tricky!
Many postcards don’t have address lines, so if someone gets upset about that, they will be upset many times. (Or learn it’s nothing to get upset about.)
But, I have to say, I was given some Etsy “artist” postcards, that I can’t use at least not in Postcrossing. The others look like photo taken from a drawing, and then printed, and one is very papery thin.
The quality can be so different, I know there is normal shop products sold also, and very nice quality cards, so if it’s fine otherwise, only “missing” address lines, I would be happy using and receiving them
I am finding it difficult to buy a variety of postcards near where I live, but I have found a little shop that stocks lovely greeting cards at a reasonable price. Is it okay to turn a greeting card into a postcard (cutting off the back)?
For me that would be okay. I think I will do that with some cards I have as well. But there are also people who don’t like that and only want “real” postcards. Most of the Times those people also don’t like handmade cards.
If the Profile seems like people wouldn’t like it I wouldn’t send auch a card. For all the other profiles I’d go for it.
(I think there is another Thread about this as Well)
If you are asking for opinions, mine would be “no.” It wouldn’t be a genuine postcard in my opinion. Here are some options for you: go online (eBay) and look for postcards from your country. Also, if you can give me a couple of days, I have some Unwritten New Zealand postcards here that you are welcome to and that I can send you…free. If interested, send me a private message with your address.
I think it is fine to turn cards into postcards. There are lots of lovely cards that would make fine postcards. I have also seen lots of creative repurposing of items into postcards.
We also have a game in this forum where participants exchange these types of cards: Front of Greeting/Folded Card Tag
As far as I know, you are allowed to send these as postcards, as long as you don’t send them whole as greeting cards within an envelope. As the others pointed out, there might be complaints if you send it to the wrong people. But it is within the rules of postcrossing and we are not required to make everyone happy.
