From the documentation on Message body size limit properties,
We could see that the property com.glide.email.max_body_bytes became obsolete AS OF LONDON Release
We now use 'glide.email.inbound.max_body_chars' instead.
- Sets the maximum body size in bytes allowed per inbound email. Ensure that the sum of this property and the glide.email.inbound.max_total_attachment_size_bytes property is well below the maximum total email size (16MB).
- Type: integer
- Default value: 1048576
As of London and later the property used is: 'glide.email.inbound.max_body_chars'
- Default value ~524k characters
- We use this new property because multi-byte character encodings have always caused confusion understanding how big a message really is.
The property glide.email.inbound.max_body_chars is used to limit excessive sys_email HTML and plain text message data when processed in the instance. This does not consider the email's headers or any attachments. If the message of the email exceeds the size defined in glide.email.inbound.max_body_chars then truncation will occur in the message data itself.
Calendar, image, octet stream and RFC822 compliant message attachments are separately limited in size by glide.email.inbound.max_total_attachment_size_bytes. If any one attachment exceeds the limit defined there then that attachment will be discarded completely and a reason will be logged. If the limit is reached prior to reading remaining attachments, the remaining attachments are not stored.
KB0521772 notes that the ServiceNow email servers have an encoded size limit of an inbound email is 75MB and 25MB for outbound email. It also notes that encoding can increase the size of the original attachment by 1.3 - 1.4x. Therefore a limit of 50MB in total for an inbound email and 18MB in total for outbound email are reasonable expectations. This total includes the entire email - HTML, plain text, attachments, headers and any encoding overhead.
If an inbound email exceeds the mail server's limit, the in-instance properties described here do not apply because the email is never read into the instance. In this case it is rejected at the mail server level.
For outbound email, the size of the encoded headers, message HTML and plaintext, and any encoding cannot exceed 25 MB. The default value for glide.email.outbound.max_total_attachment_size_bytes is 18MB which should leave sufficient capacity for a reasonably large message body, headers, and any encoding needed to produce the email.