-ERR Mailbox Locked

If you see this error when trying to login to a POP3 server, it most likely means that the server is only allowing a single connection (i.e. session) at a time for each mailbox, and than another user already has mailbox open.  It could also mean that the POP3 administrator temporarily locked the mailbox to prevent access.

Chilkat v8.6.0.0 New Features

Chilkat v8.6.0.0 is being released today. Here’s a list of the major new features/fixes. Documentation and new examples will appear soon after the new version is available at http://www.chilkatsoft.com/downloads.asp Zip: ZIP64 extensions are now supported. There is effectively no limitation on the size of individual files that can be zipped or unzipped. There is also no limitation for the total […]


This usually happens when trying to use the Chilkat 32-bit .NET 2.0 Assembly on a 64-bit system. Download and use the x64 build for the Chilkat .NET 2.0 Framework at http://www.chilkatsoft.com/downloads.asp Also, it’s likely that your development environment is 32-bit. You should add a reference to the 32-bit ChilkatDotNet2.dll, but deploy the 64-bit ChilkatDotNet2.dll to the x64 computer. Make sure […]

Chilkat C++ Libraries safe for multi-threading?

Question: Are the Chilkat C++ libraries safe for multi-threading? Answer: Yes. However, it is best practice that you don’t allow multiple threads to call methods on the same object instance at the same time. Also, objects that communicate via an Internet protocol, such as SMTP, POP3, IMAP, FTP, HTTP, etc. should not be shared between threads. It is OK to […]

No messages in POP3 mailbox?

Question: I am reading my POP3 mailbox by calling mailman.CopyMail. It returns a bundle object, but the bundle.MessageCount = 0. I know there are emails in the mailbox. What happened? Answer: The most common mistake is that you’re looking at your email using a program such as Outlook and your emails have already been downloaded and removed from the POP3 […]

C# Encrypting/Decrypting with Stream

This C# example demonstrates how to use Chilkat.Crypt2 to encrypt and decrypting using the .NET FileStream class: Chilkat.Crypt2 crypt = new Chilkat.Crypt2(); bool success = crypt.UnlockComponent("Anything for 30-day trial"); if (!success) { MessageBox.Show(crypt.LastErrorText); return; } crypt.CryptAlgorithm = "aes"; crypt.CipherMode = "cbc"; crypt.KeyLength = 128; crypt.SetEncodedIV("0000000000000000", "hex"); crypt.SetEncodedKey("abcdefghijklmnop", "ascii"); // Open input and output files as file streams… FileStream fsIn = […]

UIDL Max Size? (for POP3)

Question: I’m trying to find out the maximum size of the POP3 UIDL. I’ve found various POP3 specs, but they dont list field sizes. Do you know the max size or can you give me any links to this info? Answer: (from RFC 1939) The unique-id of a message is an arbitrary server-determined string, consisting of one to 70 characters […]

Bandwidth throttling small amounts of data.

Question: I’m sending ~50kb jpeg files alongside a very bandwidth-intensive application, so I want to make sure that my application doesn’t use more than 10kb/s, so that even those with slow connections will not have this other application impacted by mine. Answer: Concerning bandwidth throttling — it only makes sense with larger amounts of data (much more than 50K). Here’s […]