EveryCloud Technologies has included reference to this particular RFC standard with its knowledge base articles in response to many third party applications not conforming to Internet Official Protocol Standards in relation to line limits contained within the MIME content of emails (This includes MIME attachments)
On occasions, some third party senders fail to abide by the Internet Official Protocol Standard documented line length limits and alternatively attach MIME content such as PDF which a line count of 100's of thousands.
When this occurs, the MIME content may be corrupted whilst passing through our relays, because the MIME content does not conform to Internet Official Protocol Standards.
In response to the non-conformity of some third party applications, we have created exceptions on a sub-set of our relays to accomidate non-conform line limits.
The sub-set inbound load balancer with IP address 18.104.22.168 has been specifically designed to allow much larger non-conform line limits.
If you are a customer and regulalry receive non-conform line limit MIME content please contact support to ask for advise
RFC 2822 Internet Message Format April 2001
Note: This standard specifies that messages are made up of characters in the US-ASCII range of 1 through 127.
There are other documents, specifically the MIME document series [RFC2045, RFC2046, RFC2047, RFC2048, RFC2049], that extend this standard to allow for values outside of that range.
Discussion of those mechanisms is not within the scope of this standard.
Messages are divided into lines of characters. A line is a series of characters that is delimited with the two characters carriage-return and line-feed; that is, the carriage return (CR) character (ASCII value 13) followed immediately by the line feed (LF) character (ASCII value 10).
(The carriage-return/line-feed pair is usually written in this document as "CRLF".)
A message consists of header fields (collectively called "the header of the message") followed, optionally, by a body.
The header is a sequence of lines of characters with special syntax as defined in this standard.
The body is simply a sequence of characters that follows the header and is separated from the header by an empty line (i.e., a line with nothing preceding the CRLF).
2.1.1. Line Length Limits
There are two limits that this standard places on the number of characters in a line.
Each line of characters MUST be no more than 998 characters, and SHOULD be no more than 78 characters, excluding the CRLF.
The 998 character limit is due to limitations in many implementations which send, receive, or store Internet Message Format messages that simply cannot handle more than 998 characters on a line.
Ref: https://www.ietf.org/rfc/rfc2822.txt, [Online] last viewed: 06th January 2016