unknown error sending email

The log to paste when you open a support issue:
{
“error”: {
“code”: 500,
“message”: “Internal error encountered.”,
“errors”: [
{
“message”: “Internal error encountered.”,
“domain”: “global”,
“reason”: “backendError”,
“debugInfo”: “stack_entries: \”com.google.caribou.api.errors.ApiErrorInfo.build(ApiErrorInfo.java:80)\”\nstack_entries: \”com.google.caribou.api.server.messages.MessageInserter.medleyParse(MessageInserter.java:260)\”\nstack_entries: \”com.google.caribou.api.server.messages.MessageInserter.parseRawMessageToInsert(MessageInserter.java:441)\”\nstack_entries: \”com.google.caribou.api.server.messages.MessageInserter.insertMessage(MessageInserter.java:398)\”\nstack_entries: \”com.google.caribou.api.server.messages.SendMessageAction.execute(SendMessageAction.java:79)\”\nstack_entries: \”com.google.apps.framework.request.impl.InterceptorInvocation$Rpc.beforeProceed(InterceptorInvocation.java:147)\”\nstack_entries: \”com.google.apps.framework.request.impl.InterceptorInvocation.proceed(InterceptorInvocation.java:158)\”\nstack_entries: \”com.google.apps.framework.request.impl.RpcDispatcher.proceed(RpcDispatcher.java:136)\”\nstack_entries: \”com.google.apps.framework.request.impl.RpcDispatcher.proceed(RpcDispatcher.java:42)\”\nstack_entries: \”com.google.apps.framework.request.impl.AbstractDispatcher.doExecuteChain(AbstractDispatcher.java:464)\”\nstack_entries: \”com.google.apps.framework.request.impl.AbstractDispatcher.execute(AbstractDispatcher.java:303)\”\nstack_entries: \”com.google.apps.framework.request.impl.AbstractDispatcher.executeAsync(AbstractDispatcher.java:226)\”\nstack_entries: \”com.google.apps.framework.request.impl.RpcDispatcher.handleRpc(RpcDispatcher.java:126)\”\nstack_entries: \”com.google.apps.framework.request.impl.RpcScopedHandlerFactoryImpl.run(RpcScopedHandlerFactoryImpl.java:245)\”\nstack_entries: \”com.google.apps.framework.request.impl.RpcScopedHandlerFactoryImpl.access$000(RpcScopedHandlerFactoryImpl.java:45)\”\nstack_entries: \”com.google.apps.framework.request.impl.RpcScopedHandlerFactoryImpl$2.handleRequest(RpcScopedHandlerFactoryImpl.java:122)\”\nstack_entries: \”com.google.net.rpc3.impl.server.RpcServerInternalContext.runRpcInApplicationWithCancellation(RpcServerInternalContext.java:638)\”\nstack_entries: \”com.google.net.rpc3.impl.server.RpcServerInternalContext.access$400(RpcServerInternalContext.java:102)\”\nstack_entries: \”com.google.net.rpc3.impl.server.RpcServerInternalContext$3.run(RpcServerInternalContext.java:598)\”\nstack_entries: \”io.grpc.Context.run(Context.java:549)\”\nstack_entries: \”com.google.net.rpc3.impl.server.RpcServerInternalContext.runRpcInApplication(RpcServerInternalContext.java:594)\”\nstack_entries: \”com.google.net.rpc3.impl.server.RpcServerChannel$4.apply(RpcServerChannel.java:972)\”\nstack_entries: \”com.google.net.rpc3.impl.server.RpcServerChannel$4.apply(RpcServerChannel.java:957)\”\nstack_entries: \”com.google.common.util.concurrent.AbstractTransformFuture$TransformFuture.doTransform(AbstractTransformFuture.java:242)\”\nstack_entries: \”com.google.common.util.concurrent.AbstractTransformFuture$TransformFuture.doTransform(AbstractTransformFuture.java:232)\”\nstack_entries: \”com.google.common.util.concurrent.AbstractTransformFuture.run(AbstractTransformFuture.java:118)\”\nstack_entries: \”com.google.common.context.ContextRunnable.runInContext(ContextRunnable.java:89)\”\nstack_entries: \”com.google.common.context.ContextRunnable$1.run(ContextRunnable.java:78)\”\nstack_entries: \”io.grpc.Context.run(Context.java:549)\”\nstack_entries: \”com.google.tracing.GenericContextCallback.runInInheritedContext(GenericContextCallback.java:75)\”\nstack_entries: \”com.google.common.context.ContextRunnable.run(ContextRunnable.java:74)\”\nstack_entries: \”java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)\”\nstack_entries: \”java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)\”\nstack_entries: \”com.google.apps.framework.server.AbstractThreadPoolModule$InitializingThreadFactory.lambda$newThread$0(AbstractThreadPoolModule.java:605)\”\nstack_entries: \”java.lang.Thread.run(Thread.java:748)\”\n”
}
],
“status”: “INTERNAL”
}
}