diff --git a/imap-send.c b/imap-send.c
index cfd6a5120c..0d16d02029 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -1750,6 +1750,7 @@ static int curl_append_msgs_to_imap(struct imap_server_conf *server,
 
 	curl_easy_cleanup(curl);
 	curl_global_cleanup();
+	strbuf_release(&msgbuf.buf);
 
 	if (cred.username) {
 		if (res == CURLE_OK)