If you will be sharing the OneDrive folders with any of your clients, we recommend introducing them to share folders before you commence using this functionality. Our suggested best practice is for you to use the next meeting with your clients as an opportunity to take them through the process for accessing the Share Folders and the Upload Folder and to make sure they add the no-reply@sharepointonline.com email to the safe sender list in their email.
We have drafted a sample email that outlines the secure process for clients and potential issues they may encounter. You can download the Sample Email for Practices - Shared Folders.docx with this sample email at the bottom of this help article. Please feel free to use this sample as a draft for your client communication.
This information can be set up as an Email Template. Or you can also set this up, for example, as a PDF and include this as an attachment in the email that you send either before, or when you share the folders.
An FYI Admin can also use all or part of this as the basis to set up the default Email Template that is used when the folders are shared. A template needs to be set up with Merge Fields for the links to the folders and you can be set this up with any additional instructions to the client as required. Refer to Sharing the Share Folder with the Client and Including Merge Fields in Email Templates and Signatures. If you are copying and pasting the contents of the sample into an Email Template, and the images do not copy, you can copy each image individually to add it.
Note: You can share folders with the client's contacts and other email addresses as well the primary contact for the client. Therefore, Merge Fields for the addressee such as the Salutation, First Name, Last Name etc will not always be relevant for who you are sending the email to. It is recommended to set up the email with a general salutation without a name or this can be added before sending.
You can also refer your clients to our help article of any initial issues they may have - Troubleshooting initial issues with Shared Documents or Shared Folders.