diff --git a/plume-models/Cargo.toml b/plume-models/Cargo.toml
index de65b5b8..e61494ef 100644
--- a/plume-models/Cargo.toml
+++ b/plume-models/Cargo.toml
@@ -34,6 +34,7 @@ lindera-tantivy = { version = "0.7.1", optional = true }
 tracing = "0.1.22"
 riker = "0.4.2"
 once_cell = "1.5.2"
+lettre = "0.9.6"
 
 [dependencies.chrono]
 features = ["serde"]