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IMAP email access at SLAC is limited to the internal SLAC network. If you are offsite, you need to connect to VPN to use the IMAP protocol. Alternatively, you can use and configure the Owl plugin for Thunderbird. SLAC has a site license for the Owl plugin (you must use your slac.stanford.edu email address). https://intranet.slac.stanford.edu/news/2019/07/reducing-risk-cyber-attacks-certain-email-protocols
Alternatives
Other ways to read email at SLAC for linux users include:
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