The Social Media Compose tool uses the same system as Twitter to detect links. In certain situations, links are broken when the tool detects one of the following special characters:
Most non-Latin characters (Chinese, Japanese, Korean, Arabic, etc).
-For example, http://koreansite.com/page/안녕 will be detected as http://koreansite.com/page/
Special punctuation characters (special apostrophes ’, long-hyphens –, etc).
-For example, http://myblog.com/page/mycompany’s-landing-page will be detected as http://myblog.com/page/mycompany
Punctuation at the end of a URL will not be detected as part of the URL.
-For example, http://site.com/urlwithperiod. will be detected as http://site.com/urlwithperiod
Note that if you auto-publish from the COS, you will not encounter these issues. This is only when publishing directly via the Social Media Compose tool in HubSpot. To avoid these issues, if the URL is from your own website, try using a URL without these special characters. If the URL is not your own, you can try copying the URL from the Chrome URL bar and pasting it into the Compose tool which will properly format the URL and allow the full link to be detected.
The Compose tool will inform you whenever it can if your link will not be shortened properly with an error message.