Secure Attachment Policy
With Zoho Mail being a secure email service, the attachments in the emails you Send/ Receive in Zoho Mail are subject to the Secure Attachment Policy. The Secure Attachment Policy intends to protect the users from malicious files and attachments. Certain attachments containing executable/ program files may have destructive programs or malicious functions which perform phishing/ spamming/ malicious activities in the users system, and may even misuse the users identity. Hence to avoid such security threats, the emails with certain file attachments are blocked in Zoho Mail.
Attachment types that are blocked
The attachment types that are blocked by this policy include the following:
ade, adp, apk, appx, appxbundle, bat, cab, cer, chm, cmd, com, cpl, dll, dmg, exe, hlp, hta, ins, iso, isp, jar, js, jse, lib, lnk, mde, msc, msi, msix, msixbundle, msp, mst, nsh, pif, ps1, pst, reg, scr, sct, shb, sys, tmp, url, vb, vbe, vbs, vxd, wsc, wsf, wsh, terminal, cod.
Apart from the above extensions, if the file type is a executable or a script or a code file, the file cannot be sent by email.
The emails with these attachments will not be Sent/ Received via Zoho Mail and will be bounced back. This also holds true if these file types are placed in a zip file. That is, even if one file among the many in a zip archive contains any of the above mentioned file types, it will not be sent/received via Zoho Mail.
So if you try to attach any one of these file types in an email, you will receive error messages while attaching the file and the email will not be sent to your recipient(s) and will remain in your outbox.
Similarly, you also won't be receiving these file types as attachments in your inbox in Zoho Mail either.
In case you are sure that it is a trusted attachment, you can use Zoho WorkDrive or similar services, to upload the files and share them as links in your emails.
An anti-virus scanner automatically scans all the incoming emails, and processes them to bounce any email with malicious attachments or files. The emails with files that are found to have virus attachments will be bounced back and will not be relayed to the user, even if the email is from trusted contacts.