lib-smtp: client: transaction: Don't call the DATA callbacks upon failure until the transaction is complete. The transaction is not complete until smtp_client_transaction_send() is called.

lib-smtp: client: Perform output stream error handling in one place.

lib-smtp: client: Handle output stream errors in a separate function.

lib-smtp: client: Moved smtp_client_init_ssl_ctx() from smtp-client.h to smtp-client-private.h.

lib-smtp: client: Properly allow per-connection SSL configuration. Although this was already partially possible, the connection was still always using the global client SSL context.

lib-smtp: client: Make smtp_client_connection_commands_abort() more reliable by copying the command lists. Copy the current lists of queued and waiting commands and reference each command before calling smtp_client_command_abort(). Aborting one command can cause other dependent commands to be aborted (in a transaction or from submission service), which could have caused trouble in this function.

lib-smtp: client: Make smtp_client_connection_commands_fail_reply() more reliable by copying the command lists. Copy the current lists of queued and waiting commands and reference each command before calling smtp_client_command_fail_reply(). Failing one command can cause other dependent commands to be aborted (in a transaction or from submission service), which could have caused trouble in this function. Problems would likely occur at connection disconnect.

lib-smtp: client: command: Implemented callback that is called when command is fully sent.

lib-smtp: Implemented SMTP client.