Exim smarthost do not split emails

Al Gilson

• April 13, 2018 11:19

Howdy, Running cPanel v68.0.36. We pass all of our outbound Exim email to a smarthost for auditing reasons. The smarthost logs the from and to addresses for legal reasons and then delivers the email. What we're seeing: Example 1: If user Tim sends an email TO:test01@domainA.com and CC:test02@domainA.com, the system works as it should. One email is sent with 2 recipients. Example 2: If we change that up and user Tim sends an email TO:test01@domainA.com as well as CC:test03@domainB.com, Exim is sending two emails two 1 recipient each. Is it possible to have Exim simply pass the email Example 2 as one email as in Example 1? We do not want the multi-domain email split in to multiple emails. Office 365 relays multi-domain emails through our smarthost as one email. I could have a message with 60 different recipient email domains coming from O365 and our relay server sees 1 email with 60 recipients and handles it accordingly. With cPanel, using that same example, we'd have 60 emails show up with 1 recipient each. [Side note: gmail also handles this the same way as cPanel]. This is a big deal from the standpoint that Aunt Mabel sends 10x high-res pics of the grandkids to the extended family, and now we're receiving 60x the bandwidth that we should be. Outbound bandwidth is the same. Help? Thanks, - Al

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  cPanelMichael

  • April 13, 2018 16:59

  Hello @Al Gilson, Here's an Exim document with some background information about how this works: If any of the transport"s options contain a reference to $domain, only addresses with the same domain are batched.

  If batch_id is set, it is expanded for each address, and only those addresses with the same expanded value are batched. This allows you to specify customized batching conditions. Failure of the expansion for any reason, including forced failure, disables batching, but it does not stop the delivery from taking place.

  Batched addresses must also have the same errors address (where to send delivery errors), the same header additions and removals, the same user and group for the transport, and if a host list is present, the first host must be the same.
  Help with the specific modifications you'd need to make to the default Exim transport configuration is outside the scope of support we can offer, but you are welcome to look into customizing it by consulting with the Exim User's mailing list or a qualified system administrator: Thank you.

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  Al Gilson

  • April 16, 2018 13:20

  Hello @Al Gilson, Here's an Exim document with some background information about how this works:

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  cPanelMichael

  • April 16, 2018 15:51

  Hello @Al Gilson, Generally, any supported advanced Exim configuration changes will be made through "WHM >> Exim Configuration Manager >> Advanced Editor". However, you can sometimes alter how the service starts or runs by altering the /etc/sysconfig/exim file (assuming you are using CentOS 7). Here's a third-party URL where the use of that file is referenced: Setting up for Exim Thank you.

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