25-10-2021 11:53 AM - edited 25-10-2021 12:02 PM
I am getting bouncebacks when attempting to send to talktalk and tiscali domains.
Remote Server returned '550 5.4.300 Message expired -> 452 4.2.0 U3XSm2OC9Dt52U3XSmZaKT Content deferred (TT991)'
SPF records are correct - could someone advise how to fix this please?
Also ran the email header below and this came up:
on 25-10-2021 04:12 PM
Ah, well if the 3rd party gateway is rewriting the header or causing corruption of the mail, then what you're seeing is probably what the talktalk server is seeing and could result in the talktalk inbound mail server suspecting something is amiss.
I couldn't see anything obviously wrong or missing with the originating of the mail. It definitely does have DMARC set up and nothing wrong with the SPF file and I'd bet it's DKIM signed. I wouldn't expect any issues sending via outlook.com mail servers as specified on the SPF file.
I'd say you're on the right track to pin down the issue.
on 25-10-2021 03:50 PM
In parts of the header I see that dmarc/spf passes but I can also see in the same header being told dkim/dmarc = none? Would this be causing the issue? The emails in question are routed through a 3rd party gateway
on 25-10-2021 03:32 PM
I've had a look and cannot see anything amiss on the assumption that the outlook.com senders are being used. SPF and DMARC are present. My personal opinion is that I wouldn't expect to see an authentication issue for spw.com.
So, this issue is more about the content of the mail message and whether that's got a spam fingerprint or if the distribution list contains invalid email addresses or addresses that are blocking the sender. Bear in mind that not all recipients will keep an email address active and some recipients will mark as spam instead of unsubscribing. Keeping the distribution list clear of such addresses will help your deliverability,
on 25-10-2021 01:31 PM
on 25-10-2021 12:24 PM
The Content deferred error message (TT991) is because the inbound mail server feels there's something suspect about the mail message so the message has been scanned (a temporary delay to delivery) and seems not to have come out of the scanning for onward delivery (a permanent fail to deliver).
The DKIM error may be a false positive. But if the DKIM signing is corrupted or has been changed by a mail server then the mail would not be delivered.
Do you have any further information like the sending domain? The mail sending service being used?