I have the experience of Label Development and Manifest creation, in Supply Chain and Management systems like, Warehouse Management System, Parcel Manifest etc. I have a proven track record or developments of the best in class label development for the FedEx and UPS standards, too. I also have experience in the PDF based reports generation, which include different types of Barcode (such as code 128, EAN 13, SSCC-18 code structure for code 128) from Web UI, SFTP and FTP communication on event or scheduled jobs. For this development, I would recommend to use Python/ Django, which will definitely decrease the development time and increase the security of the solution.
On the Label side, I have following questions, What will be the DPI settings of the printer brother Q1160N? Can I please get the specification of this printer? Can you please also share the label layouts and type of printer. Does the printer support Zebra ZPL Emulator? My recommendation at this point would be the template creation and use the same for further printing.
For Manifest, I would need more information on the process of getting the tracking number, etc. This topic need to be discussed further in the detail.
I also have experience in SMTP Email sending with TLS and File Attachments.
I assure you, You will get best of class result with mine wide experience in the Barcodes and its challenges, plus Mine Saas based system development, which will definitely allow you for long term solution.