This is always a bad idea:
H=mx01.csx1.net [38.103.192.105] … SMTP error from remote mail server after pipelined DATA: 550 Empty envelope senders not allowed
The sender of the message (their client remember) will never find out that the email has not been delivered. In this case the mail was being forwarded, so it's impossible for us to do any better than accept the mail and then test the recipient address by trying a delivery. We had to delete the bounce message — there was nowhere to send it. ]]> Bounce messages are sent with an empty envelope sender to eliminate mail loops. For more information see: RFC 5321.
Did I mention that we would never contemplate such a foolish policy?]]>
In this case, it's the mistaken & inadvertent use of the Spamhaus PBL where the error lies. A majority of e-mail sent from a home broadband connection will contain an IP listed in the PBL. TFL (or is it Capita?) are wrongly using the Spamhaus ZEN blocklist which is an aggregate of all the lists maintained by Spamhaus. This includes the PBL.
Here's the rejection message:
REDACTED@tflcc.co.uk
host smtp.tflcc.co.uk [80.82.130.162]
SMTP error from remote mail server after end of data:
550 5.7.1 92.40.249.10 listed at zen.spamhaus.org
Received: from [92.40.249.10] (helo=dsklinux.lan) by smtp2.tvscience.co.uk with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from <REDACTED@tv-science.co.uk>) id 1dVEdi-0004i8-Wd for REDACTED@tflcc.co.uk; Wed, 12 Jul 2017 10:13:02 +0000 Received: from localhost ([127.0.0.1]:59230 helo=dsklinux.lan) by dsklinux.lan with esmtp (Exim 4.88) (envelope-from <REDACTED@tv-science.co.uk>) id 1dVEdh-0004QW-Bd for REDACTED@tflcc.co.uk; Wed, 12 Jul 2017 11:13:01 +0100
The IP of our SMTP relay server smtp2.tvscience.co.uk is [185.208.170.37] — not listed in any blocklist.
Mail administrators from TFL/Capita would do well to read and inwardly digest this Spamhaus FAQ entry; noting particularly the "⚠WARNING!" section.
For information on the correct and appropriate use of Spamhaus's blocklists see this FAQ.
For more information on SMTP trace headers, including the Received: header see: RFC 2822.]]>
Your secure connection can use port 995 for SSL access or stick with port 110 and enable STARTTLS.
You will need to accept the SSL certificate presented in order to proceed with your first e‐mail check. Use the "Accept all certificates" option where available.]]> Remember, this does not make your e-mails much more secure at all. Just your username and password now become fully protected from snooping. Only an end‐to‐end encryption scheme such as PGP or GPG can guarantee e‐mail security. ]]>
You now get 350 recipients/128MiB per month for a measly GBP20+VAT per year. ]]> Any unused quota, both bytes and recipients, roll over for a second month.
Optionally we offer DKIM signing at no extra cost.]]>
Remember also that cloud services use dynamically allocated IP addresses in many cases and are thus also unsuitable for relaying mail for the same reasons given above. Currently we do not block such computing services from sending mail to our servers; they are regarded with additional suspicion by our filters however.]]>
UPDATE: The server came back online at 1915UTC and services were reinstated shortly afterwards.]]>
.arj
files today:
Thank you for using our services!]]> The payload is a Windows™ executable as one might expect.]]>
Your order #37311131537 will be shipped on 05-09-2014.
Date: September 02, 2014. 03:09pm
Price: £191.50
Payment method: Wire transfer
Transaction number: 0466142997148E
Please find the detailed information on your purchase in the attached file (sale_2014-09-02_14-20-08_37311131537.arj)
Best regards,
Sales Department
Evelina Example
+07775 xxx xxx
WORKAROUND: If you encounter this when testing SMTP delivery, compose your own test message and send that one to yourself. ]]> Only two headers are compulsory in an SMTP e-mail: the “Date:” header & the “From:” header. Our servers refuse messages where either of these two are absent. The error message returned by our servers is, helpfully we think:
550-Mandatory header absent,
550 see: http://tools.ietf.org/html/rfc5322#section-3.6
Note: Some mailservers will return an imcomplete version of the above message — returning only part of it.
All tvScience customers using our SMTP posting accounts will have a “Date:” header added automatically should buggy software fail to add one itself.]]>
To: "Anthony Other" <another@example.com>
Currently the spam is promoting a fake goods site with the connivance of an ISP based in Hong Kong. ]]> All customers with SMTP posting accounts can request throw-away and time-limited addresses. A throw-away address is preferable in this case as a time-limited address must be promptly updated before it expires. An expired address can cause you to be temporarily locked out of your PayPal account, requiring a telephone call to PayPal customer services.]]>