The Ruby Mail gem has now been updated to include a "delete" method - even if it is for all emails on the server - there is no way of individually deleting emails so far.
Except for this - a excellent gem.
Mail is an internet library for Ruby that is designed to handle emails generation, parsing and sending in a simple, rubyesque manner.
The purpose of this library is to provide a single point of access to handle all email functions, including sending and receiving emails. All network type actions are done through proxy methods to Net::SMTP, Net::POP3 etc.
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