Does AuthSMTP support the SMTP pipelining extension?

What is SMTP pipelining?

SMTP pipelining allows the SMTP client (i.e. your email application) to send batches of SMTP commands (MAIL FROM, RCPT TO etc) without waiting for a response from the SMTP server to individual commands.

Example of SMTP transaction without SMTP pipelining

Server: 220 mail.authsmtp.com
Client: ehlo smtpclient.example.com
Server: 250-mail.authsmtp.com
….
Client: MAIL FROM:
Server: 250 2.1.0 Ok
Client: RCPT TO:
Server: 250 2.1.5 Ok
Client: RCPT TO:
Server: 250 2.1.5 Ok
Client: RCPT TO:
Server: 250 2.1.5 Ok
Client: DATA
….
Client: .
Client: QUIT
Server: 221 Bye

Example of SMTP transaction with SMTP pipelining

Server: 220 mail.authsmtp.com
Client: ehlo smtpclient.example.com
Server: 250-mail.authsmtp.com
Server: 250-PIPELINING ….
Client: MAIL FROM:
Client: RCPT TO:
Client: RCPT TO:
Client: RCPT TO:
Server: 250 2.1.0 Sender Ok
Server: 250 2.1.5 Recipient Ok
Server: 250 2.1.5 Recipient Ok
Server: 250 2.1.5 Recipient Ok
Client: DATA
….
Client: .
Client: QUIT
Server: 221 Bye

Does AuthSMTP support SMTP pipelining?

We do not support SMTP pipelining - due to the way pipelining works it can be difficult for email clients / applications to accurately track the commands / responses and it can be prone to errors.

If you have any questions about the service or you have an account and are experiencing problems sending your email please contact us.