Transferring Snapshots Through FTP
By default, snapshots are stored in folders defined as Universal Naming Convention (UNC) shares. Replication also allows you to specify a File Transfer Protocol (FTP) share instead of a UNC share. To use FTP, you must configure an FTP server and then configure a publication and one or more subscriptions to use FTP. For information about how to configure an FTP server, see the Internet Information Services (IIS) documentation. If you specify FTP information for a publication, subscriptions to that publication use FTP by default. FTP is only used with Web synchronization when the computer that is running IIS is separated from the Distributor by a firewall. In this case, FTP can be used to transfer the snapshot from the Distributor and the computer that is running IIS. (The snapshot is always transferred to the Subscriber by using HTTPS.)
We recommend that you use Microsoft Windows Authentication and a UNC share rather than an FTP share because FTP passwords must be stored, and the password is sent from the Subscriber or the computer that is running IIS when it uses Web synchronization to the FTP server in plain text. Additionally, because a single account controls access to the snapshot share, it is not possible to ensure that a Subscriber to a filtered merge publication only has access to the snapshot files from their data partition.
To deliver a snapshot through FTP
Microsoft SQL Server Management Studio: How to: Deliver a Snapshot Through FTP (SQL Server Management Studio)
Replication Transact-SQL programming: How to: Deliver a Snapshot Through FTP (Replication Transact-SQL Programming)