Bulk SMS can be an effective way to encourage donors to share their experiences and spread the word about your charity. Here are the steps to follow:

1. Collect phone numbers: First, you need to collect the phone numbers of your donors. Make sure you have their permission to contact them via SMS.
2. Choose a bulk SMS service: There are several bulk SMS services available online. Choose one that fits your needs and budget.
3. Compose your message: Keep your message brief and to the point. Encourage donors to share their experience with your charity on social media or with their friends and family. Emphasize the impact their support has made and how they can help spread awareness about your cause.
4. Personalize your message: Address your donors by their name in the message. This will make them feel more connected to your charity.
5. Include a call-to-action: Include a call-to-action in your message, such as “Share your experience with us on social media” or “Tell your friends and family about our cause.”
6. Schedule your message: Choose a date and time when most of your donors are likely to be available to receive the message.
7. Send the message: Once you have composed and scheduled your message, send it to your donors.
8. Follow up: Follow up with donors who have shared their experience or spread the word about your charity. Thank them for their support and encourage them to continue to spread awareness about your cause.
   Remember to respect your donors’ privacy and preferences. If they opt-out of receiving SMS messages, make sure you remove their phone number from your list. Also, avoid sending too many messages as it may lead to donors feeling overwhelmed and opting-out.