Cards must follow our Acceptable Use & Content Policy. In short, no hateful, threatening, sexual or infringing content.
Why some wording gets blocked
Disallowed wording is blocked automatically before a card is made. If your message is stopped, it is usually a small thing - remove anything that breaks the rules and try again. A light rephrase almost always does it. See my wording was blocked.
Reporting a card
If you receive a card that is offensive or inappropriate, tap "Report this card" at the bottom of the card, choose a reason and add any details. Reports are confidential and we review every one. Full steps are in how to report a card.