I have a C# application that sends to distribution lists via the System.Net.Mail.SmtpClient class.
The distribution lists are pulled using an LDAP query, and I store both the outlook name for the distribution list as well as the actual email of the distribution list for use.
For example: I store both #TEST Users (name) and #testusers@mycompany.com (actual email address for the distribution list)
I've run several tests with multiple distribution lists without any problems. Emails send fine without any problems.
One of my distribution lists, however, #XYZApp Users, refuses to send to anyone. This distribution list has a total of 546 recipients. None of the other lists are that large, however, I did successfully send an email with two separate distribution lists that totalled 744 recipients (one list had 438 the other 306).
Any ideas why one distribution list would work and others would not? Is there a cap on the number of recipients in a distribution list when sending emails over SMTP?