We just got a call from a US telephone number (001-, didn't get the rest of it) with an automated voice, stating that someone had sent spam mails from a server located in Berlin.
I didn't take the call, my colleague just got the first part of the number and a firm name (Something with ~computer network~ in it) It didn't seem like scam or spam, the voice just was informative with no chance to interact.
We did in fact sent our last newsletter (1,5 months ago) through a firm, located in Berlin. But all recipients opted-in for it and would not regard it as spam. We do this ~4 times/year. But it's the first time we didn't send them through our mail server.
So I would like to know who contacted us about it from the US and is this a common method to inform ? I would definitely prefer an sample e-mail sample to check some things for myself.