Countries without postcodes (updated from https://gist.github.com/kennwilson/3902548 )

COUNTRIES_WITHOUT_POSTCODES_2018.rb

COUNTRIES_WITHOUT_POSTCODES = [
    [ "Angola", "AO" ],
    [ "Antigua and Barbuda", "AG" ],
    [ "Aruba", "AW" ],
    [ "Bahamas", "BS" ],
    [ "Belize", "BZ" ],
    [ "Benin", "BJ" ],
    [ "Bolivia", "BO" ],
    [ "Botswana", "BW" ],
    [ "Burkina Faso", "BF" ],
    [ "Burundi", "BI" ],
    [ "Cameroon", "CM" ],
    [ "Central African Republic", "CF" ],
    [ "Chad", "TD" ],
    [ "Comoros", "KM" ],
    [ "Congo", "CG" ],
    [ "Congo, Democratic Republic of the", "CD" ],
    [ "Cook Islands", "CK" ],
    [ "Cote d'Ivoire", "CI" ],
    [ "Curaçao", "CW" ],
    [ "Djibouti", "DJ" ],
    [ "Dominica", "DM" ],
    [ "Equatorial Guinea", "GQ" ],
    [ "East Timor", "TL" ],    
    [ "Eritrea", "ER" ],
    [ "Fiji", "FJ" ],
    [ "French Southern Territories", "TF" ],
    [ "Gabon", "GA" ],
    [ "Gambia", "GM" ],
    [ "Grenada", "GD" ],
    [ "Guyana", "GY" ],
    [ "Heard and McDonald Islands", "HM" ],
    [ "Hong Kong", "HK" ],
    [ "Kiribati", "KI" ],
    [ "Macao", "MO" ],
    [ "Mali", "ML" ],
    [ "Mauritania", "MR" ],
    [ "Nauru", "NR" ],
    [ "Netherlands Antilles", "AN" ],
    [ "Niue", "NU" ],
    [ "North Korea", "KP" ],
    [ "Qatar", "QA" ],
    [ "Rwanda", "RW" ],
    [ "Sao Tome and Principe", "ST" ],
    [ "Seychelles", "SC" ],
    [ "Sierra Leone", "SL" ],
    [ "Solomon Islands", "SB" ],
    [ "South Sudan", "SS" ],
    [ "Suriname", "SR" ],
    [ "Syria", "SY" ],
    [ "Tokelau", "TK" ],
    [ "Togo", "TG" ],	
    [ "Tonga", "TO" ],
    [ "Tuvalu", "TV" ],
    [ "Uganda", "UG" ],
    [ "United Arab Emirates", "AE" ],
    [ "Vanuatu", "VU" ],
    [ "Yemen", "YE" ],
    [ "Zimbabwe", "ZW" ]
]

@MaxShineOn Updated

Changes based on https://en.wikipedia.org/wiki/List_of_postal_codes

Removed:

• Ireland "IE"
• Malawi "MW"
• Mauritius "MU"
• Montserrat "MS"
• Panama "PA"
• Saint Kitts and Nevis "KN"
• Saint Lucia "LC"
• Somalia "SO"
• South Africa "ZA"
• Tanzania, United Republic of "TZ"
• Timor-Leste "TL"
• Trinidad and Tobago "TT"

Added:

• Gabon
• Bolivia
• Chad
• Curaçao
• East Timor
• Heard and McDonald Islands
• South Sudan
• Togo