Lead owner and account owner fields are maintained by Marketo and read only, meaning that you cannot add value to them when they are empty, which is the case when the lead is owned by a lead queue. Do not worry, no email will read "Hey may name is Southwest" they will read "Hey my name is." if you have not set a default value in the token.
Various ways of handling this:
- Simply add real default values to your lead owner tokens in emails, setting one of the persons as one of the senders by default.
- Create a "lead owner is queue" field in SFDC and sync it to Marketo This has to be a formula (boolean) field and you need to make it "true" when the lead is owned by a queue. You will be able to use it to create a segmentation and make your email dynamic or use it in choices to send a different version of the email. This will enable you to simply write a slightly different text in your email in this case.