The good thing about sending email to sms is that you can schedule it to reach people when they are ready and willing to read and take action. In addition, they are all going to receive the messages at the same time. This feature wouldn't be possible without a specialist software or a special service to help you transform your emails into text messages.
Even if some of your recipients are outside the network coverage area or they have their mobile phone switched off, your messages are going to be delivered as soon as their phones become operational again. When they are going to see new messages, the first impulse is going to be to check their inbox to read them.