diff --git a/pyproject.toml b/pyproject.toml
index 2e2aee9..87a5df3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,7 @@ dependencies = [
     "pydantic-settings>=2.13.0",
     "markdown>=3.7",
     "pypandoc>=1.13",
-    "aiosmtplib>=3.0",
+    "aiosmtplib>=5.1.1",
     # Security floors (transitives of fastmcp; pinned to address CVEs)
     "authlib>=1.6.11",            # GHSA: CSRF when using cache
     "python-multipart>=0.0.27",   # GHSA: DoS via unbounded multipart headers
diff --git a/uv.lock b/uv.lock
index f7af57f..33ce641 100644
--- a/uv.lock
+++ b/uv.lock
@@ -16,11 +16,11 @@ wheels = [
 
 [[package]]
 name = "aiosmtplib"
-version = "5.1.0"
+version = "5.1.1"
 source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/e7/ad/240a7ce4e50713b111dff8b781a898d8d4770e5d6ad4899103f84c86005c/aiosmtplib-5.1.0.tar.gz", hash = "sha256:2504a23b2b63c9de6bc4ea719559a38996dba68f73f6af4eb97be20ee4c5e6c4", size = 66176, upload-time = "2026-01-25T01:51:11.408Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/39/ba/34f2fef90d13e21ae3f1b360da98d825c40832bb232613513be92457ff65/aiosmtplib-5.1.1.tar.gz", hash = "sha256:d9a35e9d170bc1a9f66e2fdfe7fd212f7eebb8c1581c621f79395d0bcaba7a68", size = 68123, upload-time = "2026-05-31T17:25:36.298Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/37/82/70f2c452acd7ed18c558c8ace9a8cf4fdcc70eae9a41749b5bdc53eb6f45/aiosmtplib-5.1.0-py3-none-any.whl", hash = "sha256:368029440645b486b69db7029208a7a78c6691b90d24a5332ddba35d9109d55b", size = 27778, upload-time = "2026-01-25T01:51:10.026Z" },
+    { url = "https://files.pythonhosted.org/packages/56/97/d1030d897e96c79cf0682ff93c11a2118085b3af4c27993675eda9e55da3/aiosmtplib-5.1.1-py3-none-any.whl", hash = "sha256:9d384f0c3d8906f745c1cf6819f073145bb2de8b10407905f5e2ee3389bfe6c7", size = 27937, upload-time = "2026-05-31T17:25:35.283Z" },
 ]
 
 [[package]]
@@ -690,7 +690,7 @@ dev = [
 
 [package.metadata]
 requires-dist = [
-    { name = "aiosmtplib", specifier = ">=3.0" },
+    { name = "aiosmtplib", specifier = ">=5.1.1" },
     { name = "authlib", specifier = ">=1.6.11" },
     { name = "fastmcp", specifier = ">=3.4.2,<4.0.0" },
     { name = "httpx", specifier = ">=0.28.1" },