If you need to use the uid instead of msgno use
imap_clearflag_full($stream, implode(',', $flags), '\\DELETED', ST_UID);(PHP 4, PHP 5, PHP 7, PHP 8)
imap_undelete — Unmark the message which is marked deleted
Removes the deletion flag for a specified message, which is set by imap_delete() or imap_mail_move().
imapIMAP\Connection 实例。
message_nums
       A string representing one or more messages in IMAP4-style sequence format
       ("n", "n:m", or combination of these
       delimited by commas).
      
flags
   总是返回 true。
  
| 版本 | 说明 | 
|---|---|
| 8.1.0 | 现在 imap参数接受 IMAP\Connection
  实例,之前接受有效的imapresource。 | 
If you need to use the uid instead of msgno use
imap_clearflag_full($stream, implode(',', $flags), '\\DELETED', ST_UID);The imap_delete function allows the option to use a UID for the message number but the imap_undelete function does not.