You can try this as below:
Imports Spire.Email.Pop3
’ Initialize the mailbox size variable
out_mailBoxSize = 0
Try
’ Create a POP3 client
Using pop As New Pop3Client()
’ Set host, authentication, port, and connection protocol
pop.Host = “outlook.office365.com”
pop.Username = “LeonDavisLD@outlook.com”
pop.Password = “your_password_here” ’ Replace with secure method
pop.Port = 995
pop.EnableSsl = True
' Connect to the POP server
pop.Connect()
' Get the size of the mailbox
out_mailBoxSize = pop.GetSize() ' Assign the size to the output argument
' Optionally, you can also get the number of messages if needed
' Console.WriteLine("Mailbox message count: " + pop.GetMessageCount())
' Console.WriteLine("Mailbox size: " + out_mailBoxSize + " bytes")
End Using
Catch ex As Exception
’ Handle exceptions, log error messages
Console.WriteLine("Error: " + ex.Message)
End Try