Mails marked as spam in gmail for some accounts

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http://serverfault.com – I have a couple of domains running on my VPS with VirtualMin. I have DKIM enabled, reverse DNS is setup and SPF records are added by Virtualmin. Now I have a main account (admin) which I can easily use to send emails to gmail accounts with, they don't appear in the spam folder. When I use an additional user from the same domain they ALWAYS go in to spam folder of Gmail. I tried a couple of spam checkers and they all come back like this: Main account: Summary of Results SPF check: pass DomainKeys check: neutral DKIM check: pass Sender-ID check: pass SpamAssassin chec (HowTos)