- Does cover entire mail system in centralized fashion
- NFS servers are SPOFs
- UDP & RPC are major security hazards
- Customized code is expensive to maintain
- Specific to POP3, does not cover IMAP
Obviously, my co-author doesnít necessarily agree with these points, since this was the mail system he had built, and is the basis for some mail systems which have since been installed by Sendmail, Inc. for various customers.
I would like to keep an open mind on this issue, and I have a great deal of respect for his experience and expertise, but my own personal experience so far with NFS servers has not been as rosy, and I am much more strongly disinclined to use them in this role.
My co-author is completely correct when he notes that the security issues with UDP & RPC can be resolved by putting the back-end mail servers and the NFS servers that they talk to on a private (unroutable) network, but that still doesnít eliminate my natural distaste for UDP & RPC.