uucp-old (a.k.a. uucp)

If you are running an old version of UUCP, you might have to use this delivery agent. All addresses are turned into the ! form even if they were in domain form:

user                becomes →      yourhost!user
user@host.domain    becomes →      yourhost!host.domain!user

This delivery agent can deliver to only one recipient at a time, so it can spend a lot of time transmitting duplicate messages. If at all possible, avoid using this delivery agent.

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