nodemailer 10.1.0 on Node.js NPM

10.1.0 (2026-10-10)

Pooled connections are closed after 4 minutes without a message (new idleTimeout pool option, set it to 0 to keep them open). A message whose recipients are rejected no longer closes the pooled connection, it is reset with RSET and reused, and a message is requeued when the server dropped a reused connection before any of it was sent.
connectionTimeout covers setting the session up as a whole: the DNS lookup, a proxy handshake, the TCP connection, TLS, the greeting and a STARTTLS upgrade. greetingTimeout still bounds the greeting and the STARTTLS handshake within it.
Any 421 reply ends the SMTP session. When the server closes an idle connection, SMTPConnection emits only end, not an ECONNECTION error.
A content stream that was already read or destroyed fails the message with ESTREAM instead of producing an empty attachment. Content streams of a message that fails are destroyed.
With opportunisticTLS, authentication is skipped on the unencrypted connection after a failed STARTTLS, unless forceAuth is set.
The envelope is pipelined (MAIL FROM, RCPT TO and DATA in one batch) when the server announces PIPELINING.
Errors carry originalCode (the system error code Nodemailer replaced, such as ECONNREFUSED) and, for ETIMEDOUT, timeoutType.

do not read the environment or the interface table on import (094179d)
end the SMTP session on any 421 reply and drive the envelope through one step (5638ac1)
keep ERR_ACCESS_DENIED from the Node.js permission model (8b33a3d)
let the proxy handshake and the SMTP connection share one deadline (91ed683)
mime-node: decode an SMTPUTF8 domain from its A-label form (e436f4d)
mime-node: finish an encoded part only after its output was read (ec97d8f)
qp: encode a lone CR or LF in binary quoted-printable parts (42b91d9)
smtp-connection: count the wait for the greeting against connectionTimeout (bdcd046)
smtp-connection: drop the connection when DATA is taken after a refused sender (f90fb04)
smtp-connection: refuse a second connect() call (24ba2e0)
turn Nagle off for SMTP sockets and report an early sendmail exit as such (fa9b8d3)