#313 smtp should not use [vwait]

[Colin McCormack]

Since the smtp client uses [vwait] to run asynchronously, it cannot be used within an application which also uses [vwait]. Since that includes any networking program of any complexity, the smtp client's utility is substantially reduced.

I have an event-driven smtp client written using coroutines and tcloo which doesn't suffer from this problem, to which you are welcome.

The same problem appears (on cursory grepping) to be evident in several other tcllib networking packages including ldap, ftp and comm.