Use this API to test if an email address actually exists. The method we use internally is called SMTP verification. We ping the mail server associated with the email address and the response status tells us whether an inbox exists and is able to receive incoming mail.

There are two parameters:
email (string) Email address to be verified (Example jsmith@example.com)
ext (int) (Optional) Extended information about the e-mail address (0 or 1)

The result is always a string (plain text, no JSON).

If “ext” parameter is set to 0 (= no extended information) there are only two possible results:
ok: This email address is ready to receive mails.
fail: Sending an email to this address will probably fail. For details set “ext” parameter to 1.

If “ext” parameter is set to 1 (= extended information) there are several possible results:
ok|ok: This email address is ready to receive mails.
fail|error: Delivery will probably fail, but there is no further information why it failed
fail|smtp_error: Server associated with the email address is invalid or is responding with some internal error
fail|smtp_protocol: Server associated with the email address is valid but doesn’t allow email verification
fail|unknown_email: Email address does not exist
fail|attempt_rejected: Server associated with the email address is valid but rejected the attempt to verify email
fail|relay_error: Server associated with the email address returns relay error
fail|antispam_system: Server associated with the email address is blocking email verification to avoid spam
fail|email_disabled: Email address is suspended or disabled and cannot receive emails
fail|domain_error: Server associated with the email address is not correctly installed
fail|ok_for_all: Server associated with the email address accepts any email
fail|dead_server: Server associated with the email address is dead
fail|syntax_error: Email address has a syntax error
fail|unknown: Delivery will probably fail, but there is no further information why it failed
fail|email_exists: Email address exists but there is no further information about deliverability

**All reasons given for fail can be prefixed by t_ (temporary error) or p_ (permanent error) if we have that information. **

Results will then look like this:

fail|t_error: (Temporary) Delivery will probably fail, but there is no further information why it failed
fail|t_smtp_error: (Temporary) Server associated with the email address is invalid or is responding with some internal error
fail|t_smtp_protocol: (Temporary) Server associated with the email address is valid but doesn’t allow email verification
fail|t_unknown_email: (Temporary) Email address does not exist
fail|t_attempt_rejected: (Temporary) Server associated with the email address is valid but rejected the attempt to verify email
fail|t_relay_error: (Temporary) Server associated with the email address returns relay error
fail|t_antispam_system: (Temporary) Server associated with the email address is blocking email verification to avoid spam
fail|t_email_disabled: (Temporary) Email address is suspended or disabled and cannot receive emails
fail|t_domain_error: (Temporary) Server associated with the email address is not correctly installed
fail|t_ok_for_all: (Temporary) Server associated with the email address accepts any email
fail|t_dead_server: (Temporary) Server associated with the email address is dead
fail|t_syntax_error: (Temporary) Email address has a syntax error
fail|t_unknown: (Temporary) Delivery will probably fail, but there is no further information why it failed
fail|t_email_exists: (Temporary) Email address exists but there is no further information about deliverability

or this:

fail|p_error: (Permanently) Delivery will probably fail, but there is no further information why it failed
fail|p_smtp_error: (Permanently) Server associated with the email address is invalid or is responding with some internal error
fail|p_smtp_protocol: (Permanently) Server associated with the email address is valid but doesn’t allow email verification
fail|p_unknown_email: (Permanently) Email address does not exist
fail|p_attempp_rejected: (Permanently) Server associated with the email address is valid but rejected the attempt to verify email
fail|p_relay_error: (Permanently) Server associated with the email address returns relay error
fail|p_antispam_system: (Permanently) Server associated with the email address is blocking email verification to avoid spam
fail|p_email_disabled: (Permanently) Email address is suspended or disabled and cannot receive emails
fail|p_domain_error: (Permanently) Server associated with the email address is not correctly installed
fail|p_ok_for_all: (Permanently) Server associated with the email address accepts any email
fail|p_dead_server: (Permanently) Server associated with the email address is dead
fail|p_syntax_error: (Permanently) Email address has a syntax error
fail|p_unknown: (Permanently) Delivery will probably fail, but there is no further information why it failed
fail|p_email_exists: (Permanently) Email address exists but there is no further information about deliverability