Exchanger doesn't check if the new options are different before using the cache

[PMajesty]

If you try to validate an email address without dns_lookup: :off option before trying to validate it again, but now using the option dns_lookup: :off, the gem will still try to validate by DNS, because this line doesn't check if the config is any different before deleting the proposed host:

email_address/lib/email_address/exchanger.rb

Line 14 in fe055a9

if @host_cache.has_key?(host)