rfc5321

const (
	// The maximum total length of a reverse-path or forward-path is 256
	LimitPath = 256
	// The maximum total length of a user name or other local-part is 64
	// however, here we double it, since a few major services don't respect that and go over
	LimitLocalPart = 64 * 2
	// //The maximum total length of a domain name or number is 255
	LimitDomain = 255
	// The minimum total number of recipients that must be buffered is 100
	LimitRecipients = 100
)