File used in attachment is being locked after send

I have a program listening to messages from a Message Broker (Rabbit MQ) and when a message comes in it sends an email. In the message I have a property with attachment path, which is an ftp site. I check if this is valid and download the attachment. Once downloaded I attach to the email and send.

What I am noticing is that if I send the email, move on to the next message and try to repeat the above with the SAME attachment, I get the following error System.IO.IOException: The process cannot access the file 'C:\Temp\Somepic.jpg' because it is being used by another process.

This happens at the point when I try to delete the attachment file.

I am using the MailKit as the sender.

A bit of code to help

            public async Task Consume(ConsumeContext<EmailMessage> context)
    {
        await Task.Delay(5000); // Put this in case there needs to be a delay form the last email send to allow release of file.

        _logger.LogInformation("Email recieved");

        var message = context.Message;

        var _email = _emailFactory.Create(); // _emailFactory is injected into the class. I had IFluentEmail injected before, but tried this for a fresh email each time.

        _email.BCC(message.BccAddresses)
            .CC(message.CcAddresses)
            .To(message.ToAddresses)
            .Body(message.Body, message.IsHtml);

        if (message.HasAttachment)
        {
            GetAttachment(message, _email); // Exception happens in here when it tries to delete the file from the previous send.
        }

        _logger.LogInformation("Sending Email.");

        try
        {
            var response = await _email.SendAsync();

            if (response.Successful)
            {
                _logger.LogInformation("Sent");
            }
            else
            {
                foreach (var responseErrorMessage in response.ErrorMessages)
                {
                    _logger.LogInformation(responseErrorMessage);
                }
            }
        }
        catch (Exception e)
        {
            _logger.LogError(e, "Error Sending email");
        }
    }

            private bool GetAttachment(EmailMessage message, IFluentEmail _email)
    {
        if (!string.IsNullOrEmpty(message.AttachmentPath))
        {
            _logger.LogInformation("Getting attachment");

            var pathSplit = message.AttachmentPath.Split(';');

            using var ftp = new FtpConnection(_logger, pathSplit[0], pathSplit[1], pathSplit[2]);

            if (ftp.OpenConnection())
            {
                var tempPath = @"D:\Temp\Services\Email";
                var fileName = Path.GetFileName(pathSplit[3]);
                var fullPath = Path.Combine(tempPath, fileName);

                if (File.Exists(fullPath))
                {
                    _logger.LogInformation("File exists in temp folder so deleting.");

                    try
                    {
                        File.Delete(fullPath); // IO Exception happens here
                    }
                    catch (Exception e)
                    {
                        Console.WriteLine(e);
                    }
                }

                _logger.LogInformation($"Downloading File {pathSplit[3]}.");

                ftp.DownloadFile(pathSplit[3], fullPath);

                if (File.Exists(fullPath))
                {
                    _email.AttachFromFilename(fullPath, GetContentTypeFromFileName(fullPath));
                }
                else
                {
                    _logger.LogError("Email could not be sent, file attachment did not download.");
                    return false;
                }
            }
            else
            {
                return false;
            }
        }
        else
        {
            return false;
        }

        return true;
    }

lukencode / FluentEmail

File used in attachment is being locked after send #269