My users are starting to report that messages are incurring a delay of around 5 minutes at certain times of the day. I've seen it myself a couple of times recently too.
The Exchange server's application logs regularly show the same 4 errors throughout the day:
1009 - The Microsoft Exchange Mail Submission service is currently unable to contact any Hub Transport servers in the local Active Directory site. The servers may be too busy to accept new connections at this time.
1055 - Agent factories took too long to be created. Total time was '00:00:53.7347189'. Startup time for each agent is:
Inbound Trust Agent: 00:00:00.0937506
RMS Protocol Decryption Agent: 00:00:00
ESET Filtering Agent: 00:00:00.0468753
Connection Filtering Agent: 00:00:00.0625004
Content Filter Agent: 00:00:00.4218777
Sender Id Agent: 00:00:00.0156251
Sender Filter Agent: 00:00:00.0156251
Recipient Filter Agent: 00:00:00.0156251
Protocol Analysis Agent: 00:00:50.2346965
Exclaimer Anti-spam SMTP Agent: 00:00:02.8281431.
7004 - The activation of all modules took longer than expected to complete. Total Load Time: 00:01:14.3662043 Total Start Time: 00:00:00.1144427 Load Time Breakdown:
Load Configuration Certificate and Database components:00:00:16.1130523
>> Detailed breakdown begin:
Load Database and dependents:00:00:16.1125791
>> Detailed breakdown begin:
Load Database:00:00:01.6883916
Load BatchPointComponent:00:00:00.0027458
Load ResourceManager:00:00:00.0015077
Load Database:00:00:14.4196740
>> Detailed breakdown end.
Load TransportConfiguration:00:00:00.5648737
Load CertificateComponent:00:00:00.2335263
Load RemoteDeliveryComponent:00:00:00.0000307
>> Detailed breakdown end.
Load AgentComponent:00:00:53.7634710
Load AD Configuration Readers:00:00:04.2232032
>> Detailed breakdown begin:
Load IsMemberOfResolverComponent`1:00:00:00.0025631
Load IsMemberOfResolverComponent`1:00:00:00.0016303
Load Dumpster and depedent components:00:00:00.0014948
>> Detailed breakdown begin:
Load TransportDumpster:00:00:00.0012532
Load TransportMailItemLoader:00:00:00.0001519
>> Detailed breakdown end.
Load OrarGenerator:00:00:00.0361238
Load DsnGenerator:00:00:00.0730347
Load PerfCountersLoader:00:00:00.0327751
Load LoggingComponent:00:00:00.0028632
Load PoisonMessage:00:00:00.0297465
Load DirectTrustLoader:00:00:00.0437550
Load MicrosoftExchangeRecipientLoader:00:00:00.0267723
Load ServicePrincipalNameRegistrar:00:00:00.1224909
Load CategorizerMExRuntimeLoader:00:00:04.1838409
Load MessageThrottlingComponent:00:00:00.0011895
Load RmsClientManager:00:00:00.0000150
Load ShadowRedundancy:00:00:00.0276303
>> Detailed breakdown end.
Load AD/Database Dependent Components:00:00:00.0162378
>> Detailed breakdown begin:
Load QueueManager:00:00:00.0127007
Load RpcServerComponent:00:00:00.0145635
>> Detailed breakdown end.
Load CategorizerComponent:00:00:00.1438247
Load Categorizer Dependent Components:00:00:00.1060835
>> Detailed breakdown begin:
Load SmtpInComponent:00:00:00.0135777
Load StoreDriverLoader:00:00:00.0296912
Load PickupComponent:00:00:00.0000251
Load BackgroundMailScanner:00:00:00.0000081
Load SmtpOut:00:00:00.0014091
Load NonSmtpGatewayConnectionHandler:00:00:00.0000139
Load DeliveryAgentConnectionHandler:00:00:00.0017477
Load AggregatorLoader:00:00:00.1042856
>> Detailed breakdown end.
Load BackgroundProcessingThread:00:00:00.0000203 Start Time Breakdown:
Start Configuration Certificate and Database components:00:00:00.0018650
>> Detailed breakdown begin:
Start Database and dependents:00:00:00.0017979
>> Detailed breakdown begin:
Start BatchPointComponent:00:00:00.0017697
>> Detailed breakdown end.
Start RemoteDeliveryComponent:00:00:00.0000223
>> Detailed breakdown end.
Start AD Configuration Readers:00:00:00.0334458
>> Detailed breakdown begin:
Start Dumpster and depedent components:00:00:00.0334352
>> Detailed breakdown begin:
Start TransportDumpster:00:00:00.0333994
>> Detailed breakdown end.
>> Detailed breakdown end.
Start AD/Database Dependent Components:00:00:00.0000025
Start CategorizerComponent:00:00:00.0000125
Start Categorizer Dependent Components:00:00:00.0782230
>> Detailed breakdown begin:
Start SmtpInComponent:00:00:00.0052467
Start StoreDriverLoader:00:00:00.0387261
Start PickupComponent:00:00:00.0000321
Start BackgroundMailScanner:00:00:00.0000164
Start SmtpOut:00:00:00.0001226
Start NonSmtpGatewayConnectionHandler:00:00:00.0000128
Start DeliveryAgentConnectionHandler:00:00:00.0000081
Start AggregatorLoader:00:00:00.0338760
>> Detailed breakdown end.
Start BackgroundProcessingThread:00:00:00.0007193
1022 - Anti-spam agents are enabled, but the list of internal SMTP servers is empty. If there are any MTAs between this server and the Internet, populate this list by using the Set-TransportConfig cmdlet in the Exchange Management Shell.
It looks like the Transport Service is restarting regularly, which I don't think is normal. The Exchange server gives the SMTP error, but it is the only SMTP server in the org - should I add it to the list of internalSMTPservers anyway?
Does anyone see anything from the above which would explain the delay in message delivery?