I am having the same problem with this. Any fixes/ideas?
is this the first time you're sending to them? If not whitelisted it may be in their spam?
Hi Kaitlin,
The most common cause is that you're using token values in the "From" or "Reply-To" field that don't have a valid default value set. Tokens can only use the default values when sending as a sample (unless you specify a lead record for it to sample off of) and if it can't find a valid default value, it fails trying to leave the mail server. Past that, it could be a bouncing or spam folder issue. Support could get a better grasp on what's going on by looking at your instance.
Had the same issue on a co-workers email program, double checked after seeing your reply and saw the default value was missing.
Thanks for the reminder!
Another reason this could happen is you may not have a valid unsubscribe link in the footer. We use snippets for our footers and sometimes forget to insert the appropriate country snippet when doing our testing - resulting in no email being received. I wish there was some warning/notification that Marketo would provide prior to sending emails without a valid unsubscribe link (for those that are non-operational).
A notification would be ideal.