Mail filter leads to duplication of e-mails
I use email filtering quite extensively. Mail is coming in from different accounts, and for some accounts I want the e-mails labeled with a color. For other types of e-mail I want them filed in a certain folder. The combination of these rules leads to double e-mails. My question is, how can I prevent that? Please note that my inbox is encrypted with Guard. These rules are positioned below the encryption rule.
This is an example setup of two filtering rules for which email duplication occurs:
rule 1: filter mails forwarded from gmail
IF to = email@example.com THEN set color flag = blue
rule 2: filter commercial emails
IF from = firstname.lastname@example.org THEN file into = "Advertisements"
The combination of these rules leads to two emails. If, for example, an email is sent to email@example.com from firstname.lastname@example.org then two mails appear in my mailbox: one with blue label in folder Advertisements, and one without a label in folder Advertisements. Please see the screenshot for an example.
This same behaviour is visible for different combinations of rules.
How can I prevent this email duplication from happening?