SOLVED 550 Invalid RCPT (thank you for using SPF)

WorkinOnIt

Well-Known Member
Aug 3, 2016
194
27
28
UK
cPanel Access Level
Root Administrator
Hello team

I hope you are doing great! I am wondering if you can assist with the following. I know there are many topics on this issue - though mine seems to be unique as far as I can tell !!

I keep getting mail bouncing back to one single email address and I cannot seem to identify where/what the issue is - whether this is a setting on my server - or if it is the remote server. There are no other issues on my server.

Email has been working fine to the recipient - until yesterday and now I get a bounce back (below) from my server - regardless of what I send them. There have been no changes on my server (other than a recent upgrade to version 62 build 15).

I am hoping you might be able to tell me if this is an issue with their domain or with the receiving server - or if I should add something to my cpanel config?

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

info @clientdomain.com
host mailx.theirhostdomain.com [123.45.678.910] example ip
SMTP error from remote mail server after RCPT
TO:<[email protected]>:
550 Invalid RCPT (thank you for using SPF)

I have not seen this exact message before - especially the 550 Invalid RCPT "thank you for using SPF" - which I have googled but found no matches!!

I've checked my sending server IP in blacklists and all is fine. However, I did notice that their domain does not have an SPF record. Could that be the issue - though I assumed SPF was more for "sending" rather than receiving (Sender Policy Framework). Could the absence of an SPF cause recipient issues?

Strangely - if they send me an email - I seem to be able to reply without issue. Also I tried send them an email from my personal Gmail account - that bounced too.

I have contacted their domain host and waiting for their reply - perhaps my sending server is blocked by them?

Thanks in advance.
 
Last edited:

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,913
2,202
363
Hello,

Could you search one of the affected messages in /var/log/exim_mainlog and let us know the output? EX:

Code:
exigrep [email protected] /var/log/exim_mainlog
Thank you.
 

WorkinOnIt

Well-Known Member
Aug 3, 2016
194
27
28
UK
cPanel Access Level
Root Administrator
Hello - problem solved - I finally discovered the mail host had inadvertently suspended the account without any notification to the customer! Needless to say, problem solved by moving them to a new host!
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,913
2,202
363
Hello,

I'm happy to see you were able to determine the cause of the problem. Thank you for updating us with the outcome.