diff --git a/src/lib/iostream-temp.c b/src/lib/iostream-temp.c
index 1b3583d5c0..bbdc764948 100644
--- a/src/lib/iostream-temp.c
+++ b/src/lib/iostream-temp.c
@@ -79,6 +79,36 @@ static int o_stream_temp_move_to_fd(struct temp_ostream *tstream)
 	return 0;
 }
 
+int o_stream_temp_move_to_memory(struct ostream *output)
+{
+	struct temp_ostream *tstream =
+		(struct temp_ostream *)output->real_stream;
+	unsigned char buf[IO_BLOCK_SIZE];
+	uoff_t offset = 0;
+	ssize_t ret = 0;
+
+	i_assert(tstream->buf == NULL);
+	tstream->buf = buffer_create_dynamic(default_pool, 8192);
+	while (offset < tstream->ostream.ostream.offset &&
+	       (ret = pread(tstream->fd, buf, sizeof(buf), offset)) > 0) {
+		if ((size_t)ret > tstream->ostream.ostream.offset - offset)
+			ret = tstream->ostream.ostream.offset - offset;
+		buffer_append(tstream->buf, buf, ret);
+		offset += ret;
+	}
+	if (ret < 0) {
+		/* not really expecting this to happen */
+		i_error("iostream-temp %s: read(%s*) failed: %m",
+			o_stream_get_name(&tstream->ostream.ostream),
+			tstream->temp_path_prefix);
+		tstream->ostream.ostream.stream_errno = EIO;
+		return -1;
+	}
+	i_close_fd(&tstream->fd);
+	tstream->ostream.fd = -1;
+	return 0;
+}
+
 static ssize_t
 o_stream_temp_fd_sendv(struct temp_ostream *tstream,
 		       const struct const_iovec *iov, unsigned int iov_count)
@@ -88,8 +118,18 @@ o_stream_temp_fd_sendv(struct temp_ostream *tstream,
 
 	for (i = 0; i < iov_count; i++) {
 		if (write_full(tstream->fd, iov[i].iov_base, iov[i].iov_len) < 0) {
-			tstream->ostream.ostream.stream_errno = errno;
-			return -1;
+			i_error("iostream-temp %s: write(%s*) failed: %m - moving to memory",
+				o_stream_get_name(&tstream->ostream.ostream),
+				tstream->temp_path_prefix);
+			if (o_stream_temp_move_to_memory(&tstream->ostream.ostream) < 0)
+				return -1;
+			for (; i < iov_count; i++) {
+				buffer_append(tstream->buf, iov[i].iov_base, iov[i].iov_len);
+				bytes += iov[i].iov_len;
+				tstream->ostream.ostream.offset += iov[i].iov_len;
+			}
+			i_assert(tstream->fd_tried);
+			return bytes;
 		}
 		bytes += iov[i].iov_len;
 		tstream->ostream.ostream.offset += iov[i].iov_len;
diff --git a/src/lib/iostream-temp.h b/src/lib/iostream-temp.h
index 8f16ff0e56..bf5a45d15d 100644
--- a/src/lib/iostream-temp.h
+++ b/src/lib/iostream-temp.h
@@ -25,4 +25,7 @@ struct ostream *iostream_temp_create_sized(const char *temp_path_prefix,
 struct istream *iostream_temp_finish(struct ostream **output,
 				     size_t max_buffer_size);
 
+/* For internal testing: */
+int o_stream_temp_move_to_memory(struct ostream *output);
+
 #endif
diff --git a/src/lib/test-iostream-temp.c b/src/lib/test-iostream-temp.c
index 46b5e723bc..f1e0496493 100644
--- a/src/lib/test-iostream-temp.c
+++ b/src/lib/test-iostream-temp.c
@@ -48,6 +48,31 @@ static void test_iostream_temp_create_sized_disk(void)
 	test_end();
 }
 
+static void test_iostream_temp_create_write_error(void)
+{
+	struct ostream *output;
+
+	test_begin("iostream_temp_create_sized() write error");
+	output = iostream_temp_create_sized(".", 0, "test", 1);
+
+	test_assert(o_stream_send(output, "123", 3) == 3);
+	test_assert(o_stream_get_fd(output) != -1);
+	test_assert(output->offset == 3);
+	test_assert(o_stream_temp_move_to_memory(output) == 0);
+	test_assert(o_stream_get_fd(output) == -1);
+	test_assert(o_stream_send(output, "45", 2) == 2);
+	test_assert(output->offset == 5);
+
+	const unsigned char *data;
+	size_t size;
+	struct istream *input = iostream_temp_finish(&output, 128);
+	test_assert(i_stream_read_bytes(input, &data, &size, 5) == 1 &&
+		    memcmp(data, "12345", 5) == 0);
+	i_stream_destroy(&input);
+
+	test_end();
+}
+
 static void test_iostream_temp_istream(void)
 {
 	struct istream *input, *input2, *temp_input;
@@ -120,5 +145,6 @@ void test_iostream_temp(void)
 {
 	test_iostream_temp_create_sized_memory();
 	test_iostream_temp_create_sized_disk();
+	test_iostream_temp_create_write_error();
 	test_iostream_temp_istream();
 }