Couple months ago I listed services having API for sending and receiving emails . One of them was mailgun – I was using it for a while since… yesterday. My account was locked without any valid reason. Something related with SPAM: http://documentation.mailgun.com/razor.html Reference: #rzr01. Because I know exactly what emails are being sent using my accounts (I keep track of each email coming out from the system) I was really interested how it could happen.