I'd like to start a discussion on folks opinions(*) on enforcing Envelope Sender/Recipient local-part length limits.
*opinions - because no mail operator seems to agree what it should be. For context, RFC5321 defines local-part (the bit of an envelope address to the left of the @ in an email address as) in the Size Limits and Minimums section as: 4.5.3.1. Size Limits and Minimums ... 4.5.3.1.1. Local-part The maximum total length of a user name or other local-part is 64 octets. You'll find lots of people talking about this if you google, but they mostly seem to refer to RFC822 (and subsequents) not being explicit (obviously missing the point that 822 is about the Headers while 821 is for SMTP protocol). 821, 2821, 5321 and errata have increasingly clarified this towards: - local-part max is 64 bytes (including the <) so really 63 octets - domain max is 255 octets - max total path is 256 octets We (Proofpoint Essentials) recently began enforcing <64 octets for the local-part of an envelope address. However, we are seeing a lot of senders using way longer than this. For example, looking at yesterday's traffic, 90% use 64 octets (so 65 when you include the <) jjjjAnother 3-4% live in the 65-69 octets range 2% at 73/74 octets... The largest was 217 octets None of these are 'user' addresses, they're all bounce identification, verp / recipient identifying or look like exchange distro list with AD encodings. They come from some big names, amazon, salesforce, etc. I suspect with verp/bounce addressing widely in use now, 64 octets just isn't enough these days. So, my question(s) to mailop - Is the 'local-part' definition no longer fit for purpose? Has that horse already bolted? Do you impose any limit and if so, what? Thanks, PG _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
