diff --git a/pkg/email/email.go b/pkg/email/email.go
index aa046eb..77e6425 100644
--- a/pkg/email/email.go
+++ b/pkg/email/email.go
@@ -52,7 +52,7 @@ func NewInsecure(config MailServiceConfig) *EmailService {
 	}
 }
 
-var validCommonNames = []string{"ISRG Root X1", "R3", "R11", "E5", "DST Root CA X3"}
+var validCommonNames = []string{"ISRG Root X1", "R3", "R10", "R11", "E5", "DST Root CA X3"}
 
 func NewSecure(config MailServiceConfig) *EmailService {
 	return &EmailService{