Welcome to SMTPecho.de

SMTPecho.de provides a collection of services which are useful when setting up and testing e-mail servers.

Echo e-mail

echo [at] smtpecho.de: Incoming e-mails with a valid password immediately receive a reply to the “Envelop-From”. The answer contains the e-Mail header (without subject) of the received eMail. (The subject must not contain any special chars)


Enter this password as subject in the e-mail. It is changed every 3 hours and is valid for at least 6 hours, even if a new password is already displayed on the website.

Confirmation of receipt via HTTPs

The address https://smtpecho.de/echo/[User-ID].txt can be used to check whether SMTPecho has received an e-mail and whether a reply has been sent.
(without “www” and with extension “.txt”, all in lower case letters! HTTP without TLS also works, but is uncool.)

The acknowledgements of receipt are automatically removed 120-123 minutes after the last e-mail.

User ID

The User-ID is the SHA224 from the e-mail address (all in lower case!)

echo "Vorname.Nachname@SMTPecho.de" | tr "[:upper:]" "[:lower:]" | sha224sum
User-ID = 32cd2935c292b91c192f72894521964ff39d4bbc13fa6333addf2d4d

Spam protection

Since incorrect configurations can occur when setting up e-mail servers, the e-mail server of SMTPecho.de also accepts e-mails which would normally be blocked. As protection against misuse the password in the subject line is used. In addition, the reply e-mail does not contain any content from the original e-mail, but only the mail header without subject. This should make it unattractive for spammers to abuse the service.

E-mails from SMTPecho.de only come from the following IP addresses:
IPv4 address:
IPv6 address: 2a03:4000:6:53d2::1


Please send feedback, improvement suggestions, wishes and complaints to impressum2019 [at] thju.de.