0.18.0

go-smtp v0.18.0

This release contains the following breaking changes:

- Client.Rcpt and Session.Rcpt now take an additional *RctpOptions
  argument.
- MailOptions.Size is now an int64 instead of an int.
- Server.Strict has been dropped.
- Server.ForEachConn has been dropped.

Full commit history below.

Simon Ser (15):
      Don't capitalize error messages
      Introduce cutPrefixFold
      Drop Server.Strict
      Add a more robust parser for reverse paths
      Use more robust parser for forward paths
      Add parser tests
      Drop Server.ForEachConn
      Use list for supported extensions in doc comment
      Move validateLine to client.go
      Simplify parseArgs
      Check MAIL FROM AUTH parameter mailbox
      Use int64 for MailOptions.Size
      Reject negative MAIL FROM SIZE parameters
      Move MailOptions to smtp.go
      Introduce RcptOptions

bobobo1618 (1):
      Fix parsing of MAIL FROM AUTH argument