Please advise on using OMV to receive files attached to emails and store them separately as files in a temporary storage area on a NAS. A more extensive explanation follows.
Last winter I built a DIY NAS server, planning to use OMV as its OS. But due to some personal issues, I'm only now getting around to installing an OS & configuring it. Originally I planned to use the NAS only as a media server for Plex & Kodi and to house a digital library of pdf files. I already have an older NAS (a Netgear ReadyNAS), although it is running out of space and can't run recent versions of Plex.
Currently, to access the library from a computer, tablet, or smart phone, one only needs to establish a WebDAV connection to the library's share. To maintain the library, I use Zotero with the Zotfile plugin. This works fantastically, and I intend to continue this on the new NAS.
Previously, to add items to the digital library, if I did not already have a pdf, I would create a pdf using a departmental scanner at work. The scanner would save the pdf file on a mass storage device (typically on a computer or in Google Drive). Then using Adobe Acrobat Pro, I'd make the pdf searchable with OCR and reduce its size. I'd then simply link the pdf file to its bibliographic entry in Zotero and let Zotfile do its magic: rename the file and move it to the appropriate place on the NAS drive.
But earlier this summer the department replaced and reconfigured its scanner. Instead of scanning and storing files directly on a mass storage device, the new system can only send scans as attachments to email. This creates two serious problems. First, it adds the extra steps of opening the email, finding the attachment, and saving it as a file in mass storage. Second, and even worse, email servers have (configurable) limits on how large attachments can be. Typically, 30 MB or so is the maximum. This means that most color scans are too big, and the only way to save such a scan is to break the original into smaller pieces, scan each piece, save the separate files attached to different email messages, and recombine them into a single document.
For example, using my home scanner, which can write directly to drive space, I did a test with a 36-page journal article marked up with colored highlighting. The initial file was 41MB, 31 MB after OCR, and 7 MB after reduction. But the email server rejects the large original sent directly from the departmental scanner. So I had to divide the original into multiple parts, scan each separately, open each separate email, save each part to disk, and recombine them. Only then could I run OCR on the reassembled document, reduce it, and let Zotfile store the 7 MB file on my NAS.
In general, I need to use the departmental scanner because it is much faster and more capable than my little scanner at home. I'm in the middle of digitizing my library, and soon will start scanning much larger, color documents. Because of the added steps doing this peacemeal through email, using the new system this will be much more time-consuming than necessary. So I'm thinking of configuring the new NAS as a mail server (with either no size limit or a very large limit for attachments) and using a Perl or PHP script as described here, first to check that the sender is the scanner and then to save the attachment in a temporary storage area. This would get around the email limitations and allow Zotero/Zotfile to attach each pdf to its bibliographic record and to store the pdf in the library without all the unnecessary intermediate steps.
Nonetheless, I'm a bit wary of this because I don't want to open up the server to security risks by adding mail service to its functions. Perhaps some kind of FTP service would facilitate the email file transfer more securely.
So my questions pertain to this email/ftp service. Is something like this available for OMV? Would it conflict with the server's main functions as media server and digital library storage? Are there other, better solutions than adding email (smtp) to the server's functions?