It's not an issue with the server per se.
It's more to do with how the recipients mail servers handle your incoming mail.
Make sure that your mail mail servers MX address's correctly set-up. If you can then registering with goodmail (click here) can help.
Other than that, using a dedicated IP address that couldn't have previously used for spamming helps.
And finally, at least from me, your recipients not clicking junk' or 'spam' when they receive your emails will ensure continued success.