I've tried to send a sample email to myself. I am the lead of the email, I've checked that the From address is accurate, I have tried sending the sample to a few other people in addition to myself. None of us have received the sample in our mailboxes (includes checking our spam). Kindly let me know any tricks you may have!
You can refer to this community thread and try to debug. In most cases firewall/privacy filters' been blocking the emails from Marketo. You can always use the manual person action/smart campaign to send the email to check for any possible email bounces in the person activity log. Hope this helps.
Level 10 - Community ModeratorAgree with both of the above suggestions wrt sending a real email. The only way to debug deliverability with samples is to, well. not send a sample.
However do note that samples are sent from different servers at Marketo. So it’s remotely possible that your real emails will go through, but your samples will bounce, because only the sample server is blocklisted. If the real email bounces, then that’ll almost surely be the same reason the sample bounces.
I don’t advise allow-listing/whitelisting Marketo. This disguises problems with your configuration that may be affecting recipients using the same anti-spam/anti-phishing software. There are only a handful of large providers, so it’s almost certain that some of your audience is using the same protection you are — but won’t be allowing Marketo past that protection.