diff --git a/src/lmtp/client.c b/src/lmtp/client.c
index 777929754e..2cb49898a8 100644
--- a/src/lmtp/client.c
+++ b/src/lmtp/client.c
@@ -348,4 +348,8 @@ static const struct smtp_server_callbacks lmtp_callbacks = {
 
 static const struct lmtp_client_vfuncs lmtp_client_vfuncs = {
 	.destroy = client_default_destroy,
+
+	.cmd_mail = client_default_cmd_mail,
+	.cmd_rcpt = client_default_cmd_rcpt,
+	.cmd_data = client_default_cmd_data,
 };
diff --git a/src/lmtp/client.h b/src/lmtp/client.h
index 406dfb1dd5..e359566c46 100644
--- a/src/lmtp/client.h
+++ b/src/lmtp/client.h
@@ -27,6 +27,15 @@ struct client_state {
 struct lmtp_client_vfuncs {
 	void (*destroy)(struct client *client, const char *enh_code,
 			const char *reason);
+
+	int (*cmd_mail)(struct client *client, struct smtp_server_cmd_ctx *cmd,
+			struct smtp_server_cmd_mail *data);
+	int (*cmd_rcpt)(struct client *client, struct smtp_server_cmd_ctx *cmd,
+			struct lmtp_recipient *lrcpt);
+	int (*cmd_data)(struct client *client,
+			struct smtp_server_cmd_ctx *cmd,
+			struct smtp_server_transaction *trans,
+			struct istream *data_input, uoff_t data_size);
 };
 
 struct client {
diff --git a/src/lmtp/commands.c b/src/lmtp/commands.c
index 7081df94f6..ab50ab2caa 100644
--- a/src/lmtp/commands.c
+++ b/src/lmtp/commands.c
@@ -23,11 +23,18 @@
  */
 
 int cmd_mail(void *conn_ctx,
-	     struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
-	     struct smtp_server_cmd_mail *data ATTR_UNUSED)
+	     struct smtp_server_cmd_ctx *cmd,
+	     struct smtp_server_cmd_mail *data)
 {
 	struct client *client = (struct client *)conn_ctx;
 
+	return client->v.cmd_mail(client, cmd, data);
+}
+
+int client_default_cmd_mail(struct client *client,
+			    struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
+			    struct smtp_server_cmd_mail *data ATTR_UNUSED)
+{
 	if (client->lmtp_set->lmtp_user_concurrency_limit > 0) {
 		/* connect to anvil before dropping privileges */
 		lmtp_anvil_init();
@@ -44,11 +51,21 @@ int cmd_rcpt(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
 {
 	struct client *client = (struct client *)conn_ctx;
 	struct lmtp_recipient *lrcpt;
+
+	lrcpt = lmtp_recipient_create(client, rcpt);
+
+	return client->v.cmd_rcpt(client, cmd, lrcpt);
+}
+
+int client_default_cmd_rcpt(struct client *client,
+			    struct smtp_server_cmd_ctx *cmd,
+			    struct lmtp_recipient *lrcpt)
+{
+	struct smtp_server_recipient *rcpt = lrcpt->rcpt;
 	const char *username, *detail;
 	char delim = '\0';
 	int ret;
 
-	lrcpt = lmtp_recipient_create(client, rcpt);
 
 	smtp_address_detail_parse_temp(
 		client->unexpanded_lda_set->recipient_delimiter,
@@ -99,8 +116,8 @@ cmd_data_finish(struct client *client,
 		struct smtp_server_transaction *trans)
 {
 	struct client_state *state = &client->state;
-	struct istream *input_msg, *input_local, *input_proxy;
-	struct istream *inputs[3];
+	struct istream *input_msg;
+	int ret;
 
 	i_assert(HAS_ALL_BITS(trans->flags,
 			      SMTP_SERVER_TRANSACTION_FLAG_REPLY_PER_RCPT));
@@ -111,47 +128,11 @@ cmd_data_finish(struct client *client,
 	input_msg = iostream_temp_finish(&state->mail_data_output,
 					 IO_BLOCK_SIZE);
 
-	/* formulate prepended headers for both local and proxy delivery */
-	cmd_data_create_added_headers(client, cmd, trans);
-
-	/* construct message streams for local and proxy delivery */
-	input_local = input_proxy = NULL;
-	if (client->local != NULL) {
-		inputs[0] = i_stream_create_from_data(
-			state->added_headers_local,
-			strlen(state->added_headers_local));
-		inputs[1] = input_msg;
-		inputs[2] = NULL;
-
-		input_local = i_stream_create_concat(inputs);
-		i_stream_set_name(input_local, "<lmtp DATA local>");
-		i_stream_unref(&inputs[0]);
-	}
-	if (client->proxy != NULL) {
-		inputs[0] = i_stream_create_from_data(
-			state->added_headers_proxy,
-			strlen(state->added_headers_proxy));
-		inputs[1] = input_msg;
-		inputs[2] = NULL;
-
-		input_proxy = i_stream_create_concat(inputs);
-		i_stream_set_name(input_proxy, "<lmtp DATA proxy>");
-		i_stream_unref(&inputs[0]);
-	}
-
+	ret = client->v.cmd_data(client, cmd, trans,
+				 input_msg, client->state.data_size);
 	i_stream_unref(&input_msg);
 
-	/* local delivery */
-	if (client->local != NULL) {
-		lmtp_local_data(client, cmd, trans, input_local);
-		i_stream_unref(&input_local);
-	}
-	/* proxy delivery */
-	if (client->proxy != NULL) {
-		lmtp_proxy_data(client, cmd, trans, input_proxy);
-		i_stream_unref(&input_proxy);
-	}
-	return 0;
+	return ret;
 }
 
 int cmd_data_continue(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
@@ -216,3 +197,54 @@ int cmd_data_begin(void *conn_ctx,
 	client->state.data_input = data_input;
 	return 0;
 }
+
+int client_default_cmd_data(struct client *client,
+			    struct smtp_server_cmd_ctx *cmd,
+			    struct smtp_server_transaction *trans,
+			    struct istream *data_input,
+			    uoff_t data_size ATTR_UNUSED)
+{
+	struct client_state *state = &client->state;
+	struct istream *input_local, *input_proxy;
+	struct istream *inputs[3];
+
+	/* formulate prepended headers for both local and proxy delivery */
+	cmd_data_create_added_headers(client, cmd, trans);
+
+	/* construct message streams for local and proxy delivery */
+	input_local = input_proxy = NULL;
+	if (client->local != NULL) {
+		inputs[0] = i_stream_create_from_data(
+			state->added_headers_local,
+			strlen(state->added_headers_local));
+		inputs[1] = data_input;
+		inputs[2] = NULL;
+
+		input_local = i_stream_create_concat(inputs);
+		i_stream_set_name(input_local, "<lmtp DATA local>");
+		i_stream_unref(&inputs[0]);
+	}
+	if (client->proxy != NULL) {
+		inputs[0] = i_stream_create_from_data(
+			state->added_headers_proxy,
+			strlen(state->added_headers_proxy));
+		inputs[1] = data_input;
+		inputs[2] = NULL;
+
+		input_proxy = i_stream_create_concat(inputs);
+		i_stream_set_name(input_proxy, "<lmtp DATA proxy>");
+		i_stream_unref(&inputs[0]);
+	}
+
+	/* local delivery */
+	if (client->local != NULL) {
+		lmtp_local_data(client, cmd, trans, input_local);
+		i_stream_unref(&input_local);
+	}
+	/* proxy delivery */
+	if (client->proxy != NULL) {
+		lmtp_proxy_data(client, cmd, trans, input_proxy);
+		i_stream_unref(&input_proxy);
+	}
+	return 0;
+}
diff --git a/src/lmtp/commands.h b/src/lmtp/commands.h
index 4aaa51c811..f580c8693e 100644
--- a/src/lmtp/commands.h
+++ b/src/lmtp/commands.h
@@ -5,14 +5,41 @@ struct client;
 struct smtp_server_cmd_ctx;
 struct smtp_server_cmd_helo;
 
+/*
+ * MAIL command
+ */
+
 int cmd_mail(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
 	     struct smtp_server_cmd_mail *data);
+
+int client_default_cmd_mail(struct client *client,
+			    struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
+			    struct smtp_server_cmd_mail *data ATTR_UNUSED);
+
+/*
+ * RCPT command
+ */
+
 int cmd_rcpt(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
 	     struct smtp_server_recipient *rcpt);
+
+int client_default_cmd_rcpt(struct client *client,
+			    struct smtp_server_cmd_ctx *cmd,
+			    struct lmtp_recipient *lrcpt);
+
+/*
+ * DATA command
+ */
+
 int cmd_data_continue(void *conn_ctx, struct smtp_server_cmd_ctx *cmd,
 		      struct smtp_server_transaction *trans);
 int cmd_data_begin(void *conn_ctx, struct smtp_server_cmd_ctx *cmd ATTR_UNUSED,
 		   struct smtp_server_transaction *trans,
 		   struct istream *data_input);
 
+int client_default_cmd_data(struct client *client,
+			    struct smtp_server_cmd_ctx *cmd,
+			    struct smtp_server_transaction *trans,
+			    struct istream *data_input, uoff_t data_size);
+
 #endif