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How to fix Samsung Phones not being able to send mail (ActiveSync)

In this article you will find a short how-to on how to fix the issue that some Samsung phones can receive mail, see calendars, but cannot send mail via Zimbra. Users will see messages go immediately to the outbox with a warning that the message was not sent. ActiveSync protocol version This issue affects only […]

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SMTP Smuggling in Zimbra Postfix a technical deepdive

E-mail providers like Microsoft Exchange Online and GMX allowed to pass <LF>.<CR><LF> sequence unfiltered from their outbound (sending mails) SMTP server to the inbound (receiving mails) SMTP server (postfix in our case). In the case of Postfix serving as an outbound/inbound (sending mails/receiving mails) server, it does not ignore the sequence ‘<LF>.<CR><LF>’; rather, it interprets […]

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CentOS 7 and CentOS8 Stream EOL dates are closing in

Keeping your Zimbra up-to-date by installing patches is essential for maintaining the security of your Zimbra servers. However patches are only available for supported (not end-of-life) versions. Recently the 8.8 versions of Zimbra went end-of-life and the Zimbra 9 versions are going end-of-life soon as well. Make sure all your Zimbra servers are on a […]

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Zimbra and SMTP Smuggling attack on Postfix

Recently an SMTP Smuggling attack on Postfix was published, as mentioned by the Postfix project: Days before a 10+ day holiday break and associated production change freeze, SEC Consult has published an email spoofing attack that involves a composition of email services with specific differences in the way they handle line endings other than <CR><LF>. […]

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ChatGPT knows the Zimbra API’s

Zimbra has many API’s to make it easy for system administrators to automate tasks, such as account creation, distribution list management, quota management etc. In many cases you will be using the SOAP and REST API’s or command line tools such as zmprov and zmmailbox. While there is documentation of these API’s on the Zimbra […]

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