It's known (from the DNS cache) that all DNS MX records for the domain point to dead hosts.
MailBee.NET (in MailBee.NET.dll) Version: 12.4 build 677 for .NET 4.5
public const int DeadDomainSmtpMXesInCache
It does not make sense to connect to any of the SMTP MX server of this domain
since the previous attempt to do so failed and this fact was recorded in the DNS cache.
The developer can use Clear
members of DnsCache
class to affect this behavior.