Limiting Attachment Size for Email Delivered and Received

In order to limit attachment size for incoming emails these steps can be followed,
1- Determine existing situation by using “GET” command on Exchange Management Shell
[PS] C:\Windows\System32>Get-TransportConfigClearCategories : True
DSNConversionMode : UseExchangeDSNs
GenerateCopyOfDSNFor : {5.4.8, 5.4.6, 5.4.4, 5.2.4, 5.2.0, 5.1.4}
InternalSMTPServers : {}
JournalingReportNdrTo : <>
MaxDumpsterSizePerStorageGroup : 18MB
MaxDumpsterTime : 7.00:00:00
MaxReceiveSize : unlimited
MaxRecipientEnvelopeLimit : unlimitedMaxSendSize : 10MBTLSReceiveDomainSecureList : {}
TLSSendDomainSecureList : {}
VerifySecureSubmitEnabled : False
VoicemailJournalingEnabled : True
WritingBrandingInDSNEnabled : True
Xexch50Enabled : True

Max Send Size portion shows that maximum limit is 10 MB,

2- Now we can use “SET” command to alter the value

[PS] C:\Windows\System32>Set-TransportConfig -MaxSendSize:307203- For reconfirmation again check values by “GET” command

[PS] C:\Windows\System32>Get-TransportConfigClearCategories : True
DSNConversionMode : UseExchangeDSNs
GenerateCopyOfDSNFor : {5.4.8, 5.4.6, 5.4.4, 5.2.4, 5.2.0, 5.1.4}
InternalSMTPServers : {}
JournalingReportNdrTo : <>
MaxDumpsterSizePerStorageGroup : 18MB
MaxDumpsterTime : 7.00:00:00
MaxReceiveSize : unlimited
MaxRecipientEnvelopeLimit : unlimited
MaxSendSize : 30MB
TLSReceiveDomainSecureList : {}
TLSSendDomainSecureList : {}
VerifySecureSubmitEnabled : False
VoicemailJournalingEnabled : True
WritingBrandingInDSNEnabled : True
Xexch50Enabled : True

Note: 
Same steps can be followed to change MaxReceiveSize however if you are using EDGE server roles, the change must be done on all HUB and EDGE servers.

Email Delivery Fails to My Domain Running on Exchange 2007 from only One Sender Domain

Email Delivery Fails to My Domain from only One Sender Domain
A problem occurs in Microsoft Exchange 2007 when delivery from only one sender domain fails.
You may get one of these or both error messages,
Error I

   (reason: 550 5.7.1 Sender ID (PRA) Not Permitted)

Error II
554 5.0.0 Service unavailable

Apparently everything is running OK like,
- Email delivery is failed to all users of my domain
- Email communication between your domain and this domain was normal a few days back
- Sender Domain’s reputation is “Good” or “Neutral” as per “senderbase.org” records
- Sender Domain’s SPF records are properly entered
- EDGE Synchronization is working fine
- There are no event Logs on EDGE Transport Server
- Problem comes with only one sender domain
I have studied a lot about this issue and Microsoft does not give any reason of this problem, solution is however there, even on the technet.

Solution
1- Go to EDGE Transport server and create a new custom “Receive Connector”. Provide IP and FQDN of problematic domain in the connector settings.
2- All other security & configuration settings must be exactly as your default receive connector.

After a week or so disable this connector and examine email delivery from this domain. If there is no issue keep this receive connector disabled.