There is a list in MailClient to keep the MailInfo cache, but MailClient will free it automatically, but .NET GC doesn't work like Native C++, it doesn't free the memory immediately.
I just did a test like this:
for (int i = 0; i < 1000; i++)
{
    var server = new MailServer("server address", "user", "password", ServerProtocol.Imap4);
    server.SSLConnection = true; // i also tested other protocols.
    server.Port = 993;
    var client = new MailClient("TryIt");
    client.Connect(server);
    var infos = client.GetMailInfos(); // here is 87940 emails
    Console.WriteLine("Total {0} {1} emails", i, infos.Length);
    client.Quit();
    
    // Collect all generations of memory.
    GC.Collect();
    Console.WriteLine("Memory used after full collection:   {0:N0}",
                        GC.GetTotalMemory(true));
}
here is output, from the output, GetMailInfo doesn't have memory leak, i also reviewed the source codes, it used pure manage resource in GetMailInfos.
Total 17 87940 emails
Memory used after full collection:   41,091,104
Total 18 87940 emails
Memory used after full collection:   41,090,640
Total 19 87940 emails
Memory used after full collection:   41,091,104
Total 20 87940 emails
Memory used after full collection:   41,091,104
Total 21 87940 emails
Memory used after full collection:   41,091,128
Total 22 87940 emails
Memory used after full collection:   41,091,104
Total 23 87940 emails
Memory used after full collection:   41,091,128
Total 24 87940 emails
Memory used after full collection:   41,091,104
Total 25 87940 emails
Memory used after full collection:   41,091,592
Total 26 87940 emails
Memory used after full collection:   41,091,128
Total 27 87940 emails
Memory used after full collection:   41,091,104
Total 28 87940 emails
Memory used after full collection:   41,090,640
If i don't use GC.Collect(); it used about 48MB - 160MB,  but it never exceed to upper bound,  hope this could be helpful to you.
                      Edited by user
                       
7 years ago
 | 
Reason: Not specified