I recently talked about how when sending email you should always use your ISP’s SMTP server to ensure that your email is delivered and not blocked by Spam Filters. Unfortunately this week I have had to deal with a client whose emails have been blocked because their ISP has been blacklisted in SORBS.
The blacklisting occured on the 11th of December and so far has taken 9 days for the technicians at this particular ISP to do anything. Considering this is Christmas, I suspect that there are thousands, if not millions, of dollars worth of sales being lost due to emails being discarded by Spam Filters everywhere. The unfortunate thing is that most Spam filters don’t bounce email because the majority of the time the return address has been faked and doing so would increase internet traffic exponentially. We only caught this one because we noticed emails weren’t arriving internally. If it were orders for Christmas presents then Aunty Mavis might be missing out this year.
One website you can use to check whether your ISPs mail server has been blacklisted is www.dnsstuff.com. The website has many useful tools but in particular you want to look at the Spam Database Lookup in the centre of the middle column. You will need to enter in the mail server IP address that your ISP is using which can be found in the headers of your email and look something like this: Recieved: from proxy.google.com (proxy.google.com [18.104.22.168])
If you have any red lines come up once you run the DNS Stuff tool then I would recommend informing your ISP immediately and ask them to address the issue by getting themselves removed from the Spam Database they are listed in as early as humanly possible.