On 2010-11-19 16:19, Matthias Hertzog wrote:
Hi folks!
It started about 2 weeks ago with one of our clients affected. In the meantime, the cases pile up here more and more. Some mails are completly lost after we deliver them to the bluewin MX, others 'only' loose their attachments. According to swisscom support, none of our mailservers are blocked / blacklisted there.
Can you clarify, what are the source/destination IP and email pairs? Are you sending from inside swisscom/bluewin to the SMTP servers for bluewin.ch (you state the MX) with as source a non-swisscom/bluewin address, or are you trying to send mail from swisscom/bluewin through their SMTP servers from/to what address?
As a related thing, did you ask your customers if they where notified of http://www.swisscom.ch/p25 and if that maybe is affecting delivery of emails? It being 'transparent' and just meddling with your connection in the middle, it might just do all kinds of weird things that nobody has a sight on what it is doing. And, of course still no opt-out method. I heard that you have to call techsupport, but really, I don't look forward to hanging on a phone for hours trying to educate some layer-1 support person what email is.....
from that URL: "This filter now also checks e-mail from free e-mail providers such as GMX, Google Mail and Hotmail if the e-mail is sent from a Swisscom connection"
Clearly they are doing HTTP inspection as otherwise they would not even catch most likely a percentage of the spam being sent out over those providers which are all HTTP based, that while SMTP is barely an option that only few people know about...
As a solution: provide for your customers a service: World Wide Email Delivery system
aka port 587, SSL'd with accounts on it....
Greets, Jeroen