The original poster, sunjam, is unsure how blog posts are being relayed into Discourse. Alexander suggests the “Originally posted on…” message and links to a meta thread about embedding Discourse comments on another website. However, maiki believes it is actually RSS Polling, which is a plugin for importing third-party content.
Alexander notes that embedding can also create topics automatically, but maiki prefers RSS Polling as it is less finicky. sunjam reveals that the blog is actually phplist and lacks admin access to confirm the setup.
Falco explains that the built-in embed feature is used for the official Discourse blog and is recommended when you own the blog, while RSS Polling is for importing third-party content.
Hi all, what Discourse functionality is being used to relay these blog posts into Discourse? Segunda versión de mantenimiento para Hub 3, ¡última actualización para el 23! - 
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Seems it is a part of the core application, but I haven’t been able to find it yet (searching) under our settings. Thank you for any pointers!
Do you mean the message that says “Originally posted on…”?
I’m not sure, but I think this is what you’re looking for
That would be RSS Polling:
That part is for embedding on the site: two sides of a coin integration. 
I know, but I set up the embed once and it did the job too 
Yes, that’s very true! I always forget it embeds like that.
@sunjam you have a couple of options there. I prefer the RSS polling, I find it less finicky over time; the markup for a post on a CMS may change with a theme, but the RSS feed rarely changes it’s format.
Interesting, we do not have that plugin installed. I figured out that the blog is actually phplist. Still unsure of how it is being relayed into Discourse (I lack admin access to confirm).
For our own blog at blog.discourse.org we use the built-in embed feature that @Alexander linked above, and it works perfectly for the blog use case.
The difference between the two, in a simplified way, is that the embed feature is recommended when you own the blog, and the RSS Polling is to import third-party content.