smtp-address-parser

Parse an SMTP (RFC-5321) address.


Some notes

Changes in version 1.1.0:

Domains are now checked beyond RFC-5321 syntax only

Domain names must be fully qualified; that is with at least two labels. The top-level domain must have at least two octets.

Length limitations are now checked

Total length limit of an address is 986 octets; based on a 1,000 octet SMTP line length.

See section 2.3.4. Size limits:

Domain names are limited to 255 octets, when encoded with a length byte before each label, and including the top-level zero length label. So, the effctive limit with interstitial dots is 253 octets.

Labels within a domain name are limited to 63 octets.

The above are limits of the DNS protocol, not any particular implementation.

RFC-5321 section 4.5.3.1. “Size Limits and Minimums” still says:

“To the maximum extent possible, implementation techniques that impose
no limits on the length of these objects should be used.”