Sends an SMS message to a clinic client on behalf of a clinic.

Important limitations:

• Message length: Individual carriers impose their own limits on message length, and these limits can change over time. Messages that exceed a carrier's limit may be split, truncated, or outright rejected.
• Rate limits: SMS sending is subject to overall, per-carrier, and daily rate limits. These limits are shared across all messages sent from your clinics — including messages sent by Vetcove on your behalf through other features in our platform. This endpoint enforces a limit of 20 requests per second and 200,000 requests per day per organization. These limits are not per carrier, so if your messages are not well distributed across carriers it is possible to stay within our limits while still exceeding the per-carrier limits of our third-party SMS provider.
• Trust score: Your organization is assigned a trust score by the underlying SMS provider. The content and volume of messages you send directly affects this score. Sending spammy, inappropriate, or excessive messages can lower your score, resulting in stricter rate limits and reduced deliverability across all of your clinic communications.