Diagnosing Problems with SharePoint Incoming Email

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I was recently looking through some old notes about problems I had with incoming email with SharePoint. We had a process of scanning physical mail to departmental document libraries, and we had a success rate of just over 50%. Through a week of tweaking and testing, we sustained 100% successful delivery for several months.

I was using SharePoint 2010 and Exchange 2010, but I think the settings should apply for earlier versions. At the time of writing, I don’t have access to an Exchange installation to confirm settings. These are my rough notes, hopefully of some help.

  1. Check that the document library and contact is set to allow from all senders (network scanners were not regarded as authenticated users)
  2. Check the size limits on the SharePoint send connector (Exchange -> Hub Transport -> Send Connectors -> Properties -> Maximum message size (KB))
  3. Check the size limits on SMTP receiver on SharePoint (IIS 6 Mgr -> Properties on SMTP Virtual Server -> Messages tab -> Limit message size, Limit session size)
  4. Turn off SharePoint reading RTF documents from Exchange (Exchange -> Hub Transport -> Remote Domains -> Format of original message sent as attachment to journal report: -> Exchange rich-text format -> Never use)
  5. Check for potential mail routing problems (Exchange -> Hub Transport -> Accepted Domains -> Add domain for INTERNAL RELAY) – we noticed a couple of times the scanned mail tried to go external through our mail gateway – this was the last 1% of our problems.

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17 thoughts on “Diagnosing Problems with SharePoint Incoming Email”

  1. We’ve went through these steps yet messages that are calculated as being 8mb total size in Exchange are being rejected by Sharepoint as being over the allowable limit. IIS Manager shows that we have the limit set to 10240 kb, session size is also 10240 kb, messages per connection is set to 20 and number of recipients per message is set to 100. 5 or 6mb messages go through fine. These 8mb messages deliver fine in Exchange, just not to Sharepoint. Any ideas on what we may have missed?

  2. Hi Chris,

    I suspect the problem is that the MIME encoding is making the attachments larger than the limit that IIS will allow. You may find that the attachment is actually 30-40% larger, making your 8mb file up to 11.4mb once it leaves Exchange.

    Try increasing your IIS limit to12mb (12228kb), and see if that works.

    Have a look for some more information on MIME encoding here: http://en.wikipedia.org/wiki/Base64#MIME


    1. We have the same issue as Chris – no email attachments greater than approx 8 MB make it into SharePoint. I have set our SMTP attachment size and total message size to 30 MB, so that shouldn’t be the issue and that the MIME increase isn’t the problem.

      1. Hi Eric,

        Have you had a look through all of your logs? You will need to traverse the path of the email:

        1. Has the email has been received successfully by Exchange?
        2. Has Exchange routed it successfully to the send connector?
        3. Does the SharePoint SMTP log have any trace of the message?
        4. Does the email appear on the file system of the SharePoint server? (check the various folders under the maildrop location)
        5. Are there any events in the SharePoint diagnostic logs? (ensure this is turned up to verbose)

        Hope that helps track down the problem.


    1. Hi NavazShaik,

      From your comment, it seems that you are having partial success with email coming into your document library – some work and some don’t.

      Unfortunately I can’t give you a simple answer, and you’re going to need to start investigating your system logs to track down the problem.

      Here are my tips to start looking:
      Turn up the SharePoint diagnostic logging for email events to verbose
      Check the IIS logs for the SMTP service
      Check the Exchange logs, I found the message tracking feature quite useful
      Also check the usual Windows event logs on the Exchange and SharePoint servers

      Hope that helps.


  3. How do you setup the DNS for the accepted domain? Do you add an entry that points to your SharePoint server or your Exchange server?

    1. Hi John,

      From memory, the DNS is setup to point to Exchange so it does the initial handling of email based on that domain. The Exchange connector can then route it to a specific SharePoint server.


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