Since you mentioned the server's safe id, I assume you are trying to setup cross-certification between your server and the client's, and that both of you have Notes setup using hierarchical certs. In R5, copy your server's ID onto a floppy, and in the R5 Administrator, goto the Configuration tab > Tools > Certification > ID Properties, select your server's ID, More Options > Create Safe Copy. Enter any filename for the safe ID, and you can send that to your client for them to cross-certify (they'll need to do the same for you). Since communication is between the servers only, you'll definitely want to cross-certify at the server level rather than at the cert level. Then you'll need to add their servername into your server access group and grant that server rights to the database in question. So your client will be able to access this one server only, and that database only. If the database on your server has an R5 ODS, then when your client creates the replica for the first time, they'll need to rename the file extension to .ns4 in order to be able to replicate onto their R4 server.
