diff --git a/CHANGELOG.md b/CHANGELOG.md
index e716b6e25..55ed0b35e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,9 @@
 ### Changes
 - Log server security (TLS/STARTTLS/plain) type #4005
 
+### Fixes
+- Disable SMTP pipelining #4006
+
 
 ## 1.107.0
 
diff --git a/Cargo.lock b/Cargo.lock
index 61b6edc4f..b3172d2d7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -165,9 +165,9 @@ dependencies = [
 
 [[package]]
 name = "async-smtp"
-version = "0.6.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2ade89127f9e0d44f9e83cf574d499060005cd45b7dc76be89c0167487fe8edd"
+checksum = "6da21e1dd19fbad3e095ad519fb1558ab77fd82e5c4778dca8f9be0464589e1e"
 dependencies = [
  "async-native-tls",
  "async-trait",
diff --git a/Cargo.toml b/Cargo.toml
index bbd777a48..414dd8e2d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,7 +26,7 @@ ansi_term = { version = "0.12.1", optional = true }
 anyhow = "1"
 async-imap = { git = "https://github.com/async-email/async-imap", branch = "master", default-features = false, features = ["runtime-tokio"] }
 async-native-tls = { version = "0.4", default-features = false, features = ["runtime-tokio"] }
-async-smtp = { version = "0.6", default-features = false, features = ["smtp-transport", "socks5", "runtime-tokio"] }
+async-smtp = { version = "0.5", default-features = false, features = ["smtp-transport", "socks5", "runtime-tokio"] }
 trust-dns-resolver = "0.22"
 tokio = { version = "1", features = ["fs", "rt-multi-thread", "macros"] }
 tokio-tar = { version = "0.3" } # TODO: integrate tokio into async-tar