We have upgraded to Smartermail 12.5 yesterday, however within 24 hours twice the spool has stuck with no delivery happening and the following message is logged in logs. There are no eml files in the spool folder and only HDR files are present.

The Error generated at that time is

13:10:48 [209.85.192.178][22547802] Exception: The UTC time represented when the offset is applied must be between year 0 and 10,000.
Parameter name: offset
at System.DateTimeOffset.ValidateDate(DateTime dateTime, TimeSpan offset)
at System.DateTimeOffset..ctor(DateTime dateTime)
at System.DateTimeOffset.op_Implicit(DateTime dateTime)
at System.Runtime.Caching.MemoryCacheEntryChangeMonitor.InitDisposableMembers(MemoryCache cache)
at System.Runtime.Caching.MemoryCache.CreateCacheEntryChangeMonitor(IEnumerable`1 keys, String regionName)
at #scc.#uy.#sy(DnsCacheType , String , Object )
at SmarterTools.Common.Network.DNS.PTRLookup.TryGetHostName(IPAddress ipAddress, String& hostName, String& errorText)
at SmarterTools.Common.Network.DNS.PTRLookup.TryGetHostName(String ipStr, String& hostName, String& errorText)
at MailService.TcpServerLib.SMTP.SMTPSession.GetHostName(String ipStr)
at MailService.TcpServerLib.SMTP.SMTPSession.#yeb(String )