I have notice that many emails that are not really spam, are going to the quarantine server, is there a way to increase or to decrease the level of the antispam filter?
It'd depend on why they're ending up there.
-If it's for a specific sender, you can make an exception in spamblocker:
(About spamBlocker Exceptions)https://www.watchguard.com/help/docs/help-center/en-US/Content/en-US/Fireware/services/spamblocker/spam_except_about_c.html
-You can also report false positives into our system:
(Report False Positives or Missed Spam)https://www.watchguard.com/help/docs/help-center/en-US/Content/en-US/Fireware/services/spamblocker/spam_report_false_c.html
If the mail items that are ending up there are in the suspect category, you may wish to tag or allow those messages.
Finally, failing the above you can open a support case so a support representative can help look at your logs and determine what might be wrong.
WatchGuard Customer Support
Just to confirm - these quarantine emails are listed as Confirmed Spam, and not Bulk or Suspect, correct?
sorry for the delay replying Bruce. Yes they are confirmed as spam.