Spf smtp status temperror MTA option

SPF MTA options: (2, 4, or 5)
The  MTA  option controls   whether DNS temporary errors attempting SPF  lookups are ignored (considered as successes), interpreted as temporary  failures (the default), or interpreted as permanent failures, with  values of 2, 4 (the default), or 5, respectively, controlling this. (To emphasize, this option is controlling the interpretation of DNS level  temporary errors during the attempted SPF lookups, not the  interpretation of "soft failure" results from an SPF lookup;  for that, instead see the    and   MTA options.)

The default value is 4, meaning that such DNS level temporary errors are considered to correspond to temporary SPF failures and result in  temporary rejections (deferrals) of the message. The point in the SMTP dialogue at which the SPF lookup is attempted, hence at which the DNS  error is encountered, will influence what error is returned. See the ,   ,  and    channel options. So with   set on an incoming channel, if the SPF lookup  of the domain specified on the client&#x27;s HELO or EHLO command encounters  a temporary DNS error, then with    set the  SMTP server would issue a permanent rejection: 500 5.5.2 Temporary error in SPF verification of HELO domain whereas with   set (the default), the SMTP  server would instead issue a temporary rejection: 451 4.4.3 Temporary error in SPF verification of HELO domain At the MAIL FROM: and RCPT TO: stages of the SMTP dialogue, the error text also is configurable via the    and     MTA options. So with  or    set on an incoming channel, if the SPF lookup of  the domain in the MAIL FROM: command encounters a temporary DNS error,  then with   set the SMTP server would issue a  permanent rejection (default text): 550 5.5.0 temporary error in SPF verification of MAIL FROM domain (domain) or using whatever text is configured via the   MTA option: 550 5.5.0 error_text_spf_temperror_5 whereas with  set (that is, the default)  such an error would result in merely a temporary rejection at the MAIL  FROM: stage  such as (default text): 450 4.5.1 temporary error in SPF verification of MAIL FROM domain (domain) or at the RCPT TO: stage such as: 452 4.5.1 temporary error in SPF verification of MAIL FROM domain (domain) or using whatever error text is explicitly configured via the   MTA option, hence at the MAIL FROM: stage: 450 4.5.1 error_text_spf_temperror_4 or at the RCPT TO: stage: 452 4.5.1 error_text_spf_temperror_4

See also:
 * SPF MTA options
 * error_text_spf_temperror_4 MTA Option
 * error_text_spf_temperror_5 MTA Option