You can send different parties a separate message within a solicitation (RFP, ITB, RFQ), but you can also choose to send multiple parties a message at once. You can read about what this means below.
Sending messages to multiple parties
If you send a message to multiple people you see it as a group message. The recipient only sees your name, and not that of the co-receivers. A recipient of a message will never know to whom else you have sent the message. This is referred to as a BCC (Blind Carbon Copy) recipient.
If the recipient sends a response in the message, you will receive a notification. Each message you send to multiple people becomes a separate conversation. In this separate conversation you can communicate 1-on-1 with each party.
If you want to notify all suppliers within a solicitation, you can search for suppliers under Recipients. When you select 'All Suppliers,' each of them are automatically added to the list of recipients.