TV Science Associates.

The refusal by an ISP to accept a bounce message (one with an empty envelope sender) is increasingly rare these days, but occasionally we do see it.

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.

TFL are rejecting authenticated mail relayed through our servers due to one of the SMTP Received: headers containing an IP address listed at Spamhaus.

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

All our POP3 servers now support access via encrypted connections for e‐mail retrieval.

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.

We have just doubled the byte quota for our base SMTP (e-mail) posting package.

You now get 350 recipients/128MiB per month for a measly GBP20+VAT per year.

E‐mail from dynamic IP addresses has long been refused by the wise postmaster, including ourselves. The reason is that both whitelisting & blacklisting are ineffective in this case — two tools that are essential for the world's mail administrators.

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.

The latest stable version of Movable Type Open Source is MTOS-5.2.13. You should upgrade your installations.

The server known as n6.tvscience.co.uk is currently down due to a power outage in the datacentre.

The latest stable version of Movable Type Open Source is MTOS-5.2.12. You should upgrade your installations.

The latest stable version of Movable Type Open Source is MTOS-5.2.11. You should upgrade your installations.

Most file compression formats are ripe for exploitation these days. We've seen our first .arj files today:

Thank you for using our services!
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