Objective-C

Get the POP3 UIDL of an Email

Demonstrates the read-only Chilkat Email.Uidl property, which contains the unique message identifier assigned by a POP3 server; the value is also represented by the X-UIDL header field. This example sets X-UIDL directly to illustrate how it maps to the Uidl property (normally the value comes from the POP3 server during download).

Background: A UIDL ("unique ID listing") is POP3's stable identifier for a message in a mailbox — it stays the same across sessions, so a client can remember which messages it has already downloaded and avoid fetching them again. Note this is POP3-specific: IMAP uses its own UID instead, which Chilkat stores in the ckx-imap-uid header rather than in Uidl.

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Objective-C

#import <CkoEmail.h>

//  Demonstrates the read-only Email.Uidl property, which contains the unique message
//  identifier assigned by a POP3 server.  The value is represented by the X-UIDL header
//  field.  Here we set X-UIDL directly to show how it maps to the Uidl property.

CkoEmail *email = [[CkoEmail alloc] init];

//  Normally the POP3 server assigns this; we set it here for demonstration.
[email AddHeaderField: @"X-UIDL" fieldValue: @"0000000123abcdef"];

NSLog(@"%@%@",@"Uidl = ",email.Uidl);