While checking the senderbase stats for one of the domains I'm responsible for, I got some very strange data:

Report on domain: al-systems.com
Volume Statistics for this Domain
Magnitude Vol Change vs. 30 Day
Last day 3.6 193%
Last 30 days 3.2

However, if I check the mailservers seperately, I get:

Report on IP address: 195.243.162.145
Volume Statistics for this IP
Magnitude Vol Change vs. Average
Last day 3.6 -60%
Last 30 days 2.9 -93%
Average 4.0

Report on IP address: 195.243.162.146
Volume Statistics for this IP
Magnitude Vol Change vs. Average
Last day 3.3 -61%
Last 30 days 2.8 -88%
Average 3.7

How's that possible? Both mailservers show a decrease in traffic, whereas the main domain shows an increase?

BTW, those two servers are the only ones that may send outbound mails - I doublechecked the firewall already :-)

Any ideas would be greatly appreciated.

I'm not sure how senderbase calculates those statistics exactly. It could be that for the domain statistics, they are including all emails which CLAIM to be from that domain, since there is no real way to reliably verify that a given sending server is or isn't allowed to send email for a particular domain, unless that domain is using SPF or DomainKeys.

You could try emailing senderbase about it, but I have emailed them several times in the past regarding incorrect/stale whois information and have never gotten a response back, so that may just be a waste of your time.

I have seen the same data and asked the same question. And to repeat Telarin's experience, the few times I did get a reply, there wasn't an answer in all the words provided in those replies. Any attempt to follow-up received that "blank, nothing" noise. That's all the help I can offer.

Well, this is getting stranger every day. Today it shows a 262% increase vs. the last 30 days for the domain, whereas the mailservers still show a decrease.

But since there seems to be little to no help from senderbase, I'll probably just write this off as "I don't know what's going on, but as long as the numbers are still within normal range, should I really care?"

Nevertheless, thanks for your help!

A. Friend