When you send a proposal, your best bet is to make it multimodal. If you send an email, accompany it with a voicemail to check in. Say, "Hello, _____. I just sent you the proposal as promised. Please confirm that you've received it. If I don’t hear from you sooner, I'll get back with you in a couple of days so we can chat through it."
It’s less likely for a person to miss a voicemail than an email, which can get lost among the hundreds that pass through the typical inbox each week. This will be their reminder and your insurance. You can text; however, I wouldn’t recommend it unless you have their permission. The good news is, more and more executives prefer text over anything else, so don’t be afraid to ask. Texting is easy, in the moment, and less likely to be overlooked.
Regardless of which mode you use, these should be very short messages. Let them know you’ll be back in touch. If your prospect knows you're going to call back in a few days, they’ll be more likely to read your proposal and prepare themselves. It also takes the pressure off your second contact.
If you think your prospect is the kind of person who’ll call back, you should have notes prepared in order to walk them through any questions or additional information they’ll need. If not, call them back as you promised. One good tactic is to be genuinely enthusiastic. You might say, “Hi John, I promised to call you back in a couple days so we could walk through the proposal I sent earlier this week and address any questions/comments you might have. Is this a convenient time for us to chat?”
Let's assume that you get back to your prospect 2-4 days later. The pitch you have is the same. Still, make sure you emphasize that good things are happening. Stay open regardless of whether it’s a good time or not. The important thing is to facilitate each touch that will bring you closer to the sale.