Address is valid

Address is valid but a DNS check was not successful

Address is valid for SMTP but has unusual elements

Address is valid within the message but cannot be used unmodified for the envelope

Address contains deprecated elements but may still be valid in restricted contexts

The address is only valid according to the broad definition of RFC 5322. It is otherwise invalid

All finer grained error checking is turned on. Address containing errors or warnings is considered invalid. A specific email status code will be returned indicating the error/warning of the address.

Address is either considered valid or not, no finer grained error checking is performed. Returned email status code will be either Error or Valid.

Address containing warnings is considered valid, that is, any status code below 16 is considered valid.

Address is invalid for any purpose

Address is valid

Could not find an MX record for this domain but an A-record does exist

Could not find an MX record or an A-record for this domain

Address is valid but at a Top Level Domain

Address is valid but the Top Level Domain begins with a number

Address is valid but contains a quoted string

Address is valid but at a literal address not a domain

Address is valid but contains a :: that only elides one zero group

Address contains comments

Address contains Folding White Space

The local part is in a deprecated form

Address contains an obsolete form of Folding White Space

A quoted string contains a deprecated character

A quoted pair contains a deprecated character

Address contains a comment in a position that is deprecated

A comment contains a deprecated character

Address contains a comment or Folding White Space around the @ sign

Address is RFC 5322 compliant but contains domain characters that are not allowed by DNS

Address is too long

The local part of the address is too long

The domain part is too long

The domain part contains an element that is too long

The domain literal is not a valid RFC 5321 address literal

The domain literal is not a valid RFC 5321 address literal and it contains obsolete characters

The IPv6 literal address contains the wrong number of groups

The IPv6 literal address contains too many :: sequences

The IPv6 address contains an illegal group of characters

The IPv6 address has too many groups

IPv6 address starts with a single colon

IPv6 address ends with a single colon

A domain literal contains a character that is not allowed

Address has no local part

Address has no domain part

The address may not contain consecutive dots

Address contains text after a comment or Folding White Space

Address contains text after a quoted string

Extra characters were found after the end of the domain literal

The address contains a character that is not allowed in a quoted pair

Address contains a character that is not allowed

A quoted string contains a character that is not allowed

A comment contains a character that is not allowed

The address cannot end with a backslash

Neither part of the address may begin with a dot

Neither part of the address may end with a dot

A domain or subdomain cannot begin with a hyphen

A domain or subdomain cannot end with a hyphen

Unclosed quoted string

Unclosed comment

Domain literal is missing its closing bracket

Folding White Space contains consecutive CRLF sequences

Folding White Space ends with a CRLF sequence

Address contains a carriage return that is not followed by a line feed