There are many newsletters, a few of them I can recommend:
I'd compare it to reading international newspapers, narrowed down to IT-Security news only and to a very short summary of each topic. Keeps you informed about things that happen outside your tiny view of the world and about topics which are not covered by your daily website like https://www.heise.de/security/
"SANS NewsBites is a semiweekly high-level executive summary of the most important news articles that have been published on computer security during the last week. Each news item is very briefly summarized and includes a reference on the web for detailed information, if possible."
SANS @RISK: The Consensus Security Alert
"@RISK provides a reliable weekly summary of (1) newly discovered attack vectors, (2) vulnerabilities with active new exploits, (3) insightful explanations of how recent attacks worked, and other valuable data"
"A public, vendor-neutral forum for detailed discussion of vulnerabilities and exploitation techniques, as well as tools, papers, news, and events of interest to the community. The relaxed atmosphere of this quirky list provides some comic relief and certain industry gossip. More importantly, fresh vulnerabilities sometimes hit this list many hours or days before they pass through the Bugtraq moderation queue."
=> https://seclists.org/fulldisclosure/ Registration for newsletter