Parse an SMTP (RFC-5321) address.
Length limitations are not checked.
Technically a local-part of a Mailbox address is limited to 64 octets or less, see: https://tools.ietf.org/html/rfc5321#section-188.8.131.52.1
Also, domain names are limited to 255 octets, see: https://tools.ietf.org/html/rfc5321#section-184.108.40.206.2
And individual labels within a domain name are limited to 63 octets or less, see: https://tools.ietf.org/html/rfc1035 section 2.3.4. Size limits
However, RFC-5321 section 220.127.116.11. “Size Limits and Minimums” says:
“To the maximum extent possible, implementation techniques that impose no limits on the length of these objects should be used.”