If you installed or upgraded to Zimbra version 9.0.0.P34, 8.8.15.P41, 10.0.2 or higher, Zimbra will use OpenSSL 3.0.x and FIPS compliance for OpenSSL will be enabled by default. To check if your Zimbra OpenSSL is using FIPS you can run the following command, that should fail with Error setting digest: /opt/zimbra/common/bin/openssl md5 /dev/null There are […]
Tag Archives | email security
Sending incoming email with bad headers to Junk
Email is always evolving and recently Gmail has started to reject email with bad headers for some customers. Rejecting email with bad headers may help protect against DKIM replay attacks (more on replay attacks in an upcoming blog). When we are talking about messages with bad headers, we mean messages that are not compliant with […]
New phishing attacks may use .zip, .mov and other new Internet domains
Beware of fraudulent activities using the newly launched .zip and .mov top-level domains. Phishing attacks have already targeted well-known brands like Microsoft and Okta. Apart from phishing, the new .zip and .mov TLDs have also been used for various malicious purposes like hosting zip bombs, redirecting to YouTube videos, and offering file compression services. Here […]
A Milter for using Spamhaus HBL with Zimbra Postfix
In this article you will learn how to use Spamhaus Hash Blocklist (HBL) to improve email protection in Zimbra. For a long time administrators of Zimbra have relied on Spamhaus to fight incoming spam by configuring Postfix using traditional blacklists. These traditional blocklists work by blocking IP (ranges) and domains of known spammers. When an […]
Improve email Zimbra protection with Spamhaus HBL
In this article you will learn how to use Spamhaus Hash Blocklist (HBL) to improve email protection in Zimbra. For a long time administrators of Zimbra have relied on Spamhaus to fight incoming spam by configuring Postfix using traditional blacklists. These traditional blocklists work by blocking IP (ranges) and domains of known spammers. When an […]
Did you know? Zimbra Postscreen provides additional protection against mail server overload
In Zimbra you can optionally enable Postscreen as an additional Anti-SPAM strategy. Postscreen will offer additional protection against mail server overload. One postscreen process handles multiple inbound SMTP connections and decides which clients may talk to a Post-fix SMTP server process. By keeping spambots away, postscreen leaves more SMTP server processes available for legitimate clients […]