SMTP Service Configuration

Address and Port

Name: INBUCKET_SMTP_ADDR
Default: 0.0.0.0:2500

The IPv4 address and TCP port number the SMTP server should listen on, separated by a colon. Some operating systems may prevent Inbucket from listening on port 25 without escalated privileges. Using an IP address of 0.0.0.0 will cause Inbucket to listen on all available network interfaces.

Greeting Domain

Name: INBUCKET_SMTP_DOMAIN
Default: inbucket

The domain used in the SMTP greeting:

220 domain Inbucket SMTP ready

Most SMTP clients appear to ignore this value.

Maximum Recipients

Name: INBUCKET_SMTP_MAXRECIPIENTS
Default: 200

Maximum number of recipients allowed (SMTP RCPT TO phase). If you are testing a mailing list server, you may need to increase this value. For comparison, the Postfix SMTP server uses a default of 1000, it would be unwise to exceed this.

Maximum Message Size

Name: INBUCKET_SMTP_MAXMESSAGEBYTES
Default: 10240000 (10MB)

Maximum allowable size of a message (including headers) in bytes. Messages exceeding this size will be rejected during the SMTP DATA phase.

Default Recipient Accept Policy

Name: INBUCKET_SMTP_DEFAULTACCEPT
Default: true
Values: true or false

If true, Inbucket will accept mail to any domain unless present in the reject domains list. If false, recipients will be rejected unless their domain is present in the accept domains list.

Accepted Recipient Domain List

Name: INBUCKET_SMTP_ACCEPTDOMAINS
Default: None
Values: Comma separated list of recipient domains
Example: localhost,mysite.org

List of domains to accept mail for when INBUCKET_SMTP_DEFAULTACCEPT is false; has no effect when true.

Rejected Recipient Domain List

Name: INBUCKET_SMTP_REJECTDOMAINS
Default: None
Values: Comma separated list of recipient domains
Example: reject.com,gmail.com

List of domains to reject mail for when INBUCKET_SMTP_DEFAULTACCEPT is true; has no effect when false.

Rejected Origin Domain List

Name: INBUCKET_SMTP_REJECTORIGINDOMAINS
Default: None
Values: Comma separated list of origin domains
Example: reject.com,gmail.com

List of domains to reject mail from. This list is enforced regardless of the INBUCKET_SMTP_DEFAULTACCEPT value.

Enforcement takes place during evalation of the MAIL FROM SMTP command, the origin domain is extracted from the address presented and compared against the list. It does not take email headers into account.

Default Recipient Store Policy

Name: INBUCKET_SMTP_DEFAULTSTORE
Default: true
Values: true or false

If true, Inbucket will store mail sent to any domain unless present in the discard domains list. If false, messages will be discarded unless their domain is present in the store domains list.

Stored Recipient Domain List

Name: INBUCKET_SMTP_STOREDOMAINS
Default: None
Values: Comma separated list of recipient domains
Example: localhost,mysite.org

List of domains to store mail for when INBUCKET_SMTP_DEFAULTSTORE is false; has no effect when true.

Discarded Recipient Domain List

Name: INBUCKET_SMTP_DISCARDDOMAINS
Default: None
Values: Comma separated list of recipient domains
Example: recycle.com,loadtest.org

Mail sent to these domains will not be stored by Inbucket. This is helpful if you are load or soak testing a service, and do not plan to inspect the resulting emails. Messages sent to a domain other than this will be stored normally. Only has an effect when INBUCKET_SMTP_DEFAULTSTORE is true.

Network Idle Timeout

Name: INBUCKET_SMTP_TIMEOUT
Default: 300s
Values: Duration ending in s for seconds, m for minutes

Delay before closing an idle SMTP connection. The SMTP RFC recommends 300 seconds. Consider reducing this significantly if you plan to expose Inbucket to the public internet.

TLS Support Availability

Name: INBUCKET_SMTP_TLSENABLED
Default: false
Values: true or false

Enable the STARTTLS option for opportunistic TLS support

TLS Private Key File

Name: INBUCKET_SMTP_TLSPRIVKEY
Default: cert.key
Values: filename or path to private key
Example: server.privkey

Specify the x509 Private key file to be used for TLS negotiation. This option is only valid when INBUCKET_SMTP_TLSENABLED is enabled.

TLS Public Certificate File

Name: INBUCKET_SMTP_TLSCERT
Default: cert.crt
Values: filename or path to the certificate key
Example: server.crt

Specify the x509 Certificate file to be used for TLS negotiation. This option is only valid when INBUCKET_SMTP_TLSENABLED is enabled.

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