In this post, we’ll show you how doing selective Postfix rate limiting will improve your Zimbra system’s email deliverability. Various trade press accounts have reported that COVID resulted in email volumes essentially doubling. For large email providers, especially the free email providers like Gmail, Yahoo and Outlook.com, they have had …
Increasingly we are seeing distributed brute force login attacks on our Zimbra hosting environment, as well as on our on-premises customers’ Zimbra systems. These login attempts typically come from 10 to 20 or so different IP addresses from around the globe, and are infrequent enough that Zimbra’s Denial of Service …
To date, when most people think of anti-spam, they think of blocking inbound spam. Most people don’t think about taking steps to ensure that their domain won’t be spoofed by bad actors, often because they presume that email that spoofs their domain would be blocked by the recipients. But that’s …
Do any of these describe your Zimbra system? You have a large mail store (1TB or more) Your Zimbra system is busy with a lot of inbound and/or outbound emails every day You keep backups for a long time You believe you have plenty of RAM but you are finding …
Each year, we read in the various data breach reports that email remains the Number One attack vector used for phishing, whaling, malware distribution and other scams. In this blog post, continuously updated since March 2019, we describe how we supplement the various open-source anti-spam capabilities that ship with Zimbra …
We use a variety of monitoring tools to make sure we know what’s what with our Zimbra Hosting environment, and we are pleased to announce that customers now have access to our “outside-in” monitoring (courtesy of UptimeRobot). You can see the uptime report for all of our Zimbra’s public-facing services …
Email is one of the top attack vectors for getting inside an organization, and it is a known fact that we are more likely to open an email that purports to come from someone we know. The spammers of course know this too, and recently, they have been exploiting it …
Zimbra’s DoSFilter (Denial of Service Filter) is a mechanism to throttle or block IP addresses that have a repeated number of failed logins to your Zimbra system. Zimbra’s Classes of Service include a Failed Login Lockout policy that will put a mailbox in Locked Out mode, hopefully before a brute …
:: Zimbra and DNS Challenges :: Zimbra, like all email servers, is highly reliant on performant DNS not only to be able to send and receive email, but also to be able to perform anti-spam tasks. Certain components of Zimbra even use DNS to find other Zimbra components and servers …
