Sorry for the delay in response.
As per your query, when you send the document for signature from Adobe Sign account, some of the users do not receive it.
Did you check with the signers if they can find the document in the spam in their email account?
How exactly you get to know that the signers are not receiving the document?
Try once to check if you have added the correct email address while sending the document.
In Adobe Sign, go to Manage tab > Out for Signature.
Then select the document from the list. Then select the "History" tab from the preview window at extreme right.
There you can check who has already signed the document and whose signature is still pending.
Check if the email address for all the signers is correct.
If you are still experiencing this issue, please get in touch with the support team.
This is something that needs to be checked.
Find below the steps to contact support:
• Login to your Adobe Sign account directly via https://corporate.na1.echosign.com/account/home.
• Once logged in, check the upper right corner of the page and click the question mark icon.
• It will re-direct you to the page where you get the option to create the support case or to start a chat with the team.
• If you've never logged in this way, use the forgot password option on the login link to set your password.
Let us know if you need any help.