There is a limit of 300 pending authorizations/account.
For domains hosted on our servers everthing is fine.
However for domains hosted on third party servers the number of pending authorizations is related to customer’s response time. Think of a customers which starts a issuance process but does not complete the authorization process.
If you have 300 lazy customers your account will get blocked.
The only possibility to circumvent this problem is to close authorization requests after some time (e.g. 4 hours). I would close the requests by a failed validation.
I am afraid if failed validations (as described) would count against this limit. Do they?