At the present time, Mailbird does not offer Filters/ Rules capability. However, we are developing such capability, and a filters/rules feature will be available in an upcoming major Mailbird release.
Until that release, an interim solution exists if you use IMAP in Mailbird. Most email providers, e.g., Gmail, provide filters/rules, which you can configure on your email providers website or phone app. Setting rules or filters with your email provider generally offers you greater functionality than most email clients like Mailbird can provide. This way is much more convenient and powerful than setting it up in an email client. Because not only that the filter will run 24/7, you only need to set it up once for all your email clients in all your devices, including mobile ones.