Temporarily add net-gems as dependencies of frameworks that use mail

In Ruby 3.1 those gems were dropped from the stdlib, so they need to be
explicitly installed. Mail should be doing this for us, but since it
cares about Ruby < 2.6, and those gems can't be installed there, they
can't add them to the gemspec without dropping support to old rubies.

Since we don't care about Ruby < 2.7, we can just require them in all
frameworks that use mail.

Gemfile

@@ -35,12 +35,6 @@ gem "terser", ">= 1.1.4", require: false
 # Explicitly avoid 1.x that doesn't support Ruby 2.4+
 gem "json", ">= 2.0.0"
 
-# net-smtp, net-imap and net-pop were removed from default gems in Ruby 3.1, but is used by the `mail` gem.
-# So we need to add them as dependencies until `mail` is fixed: https://github.com/mikel/mail/pull/1439
-gem "net-smtp", require: false
-gem "net-imap", require: false
-gem "net-pop", require: false
-
 group :rubocop do
   gem "rubocop", ">= 0.90", require: false
   gem "rubocop-minitest", require: false

Gemfile.lock

@@ -36,12 +36,18 @@ PATH
       activestorage (= 7.1.0.alpha)
       activesupport (= 7.1.0.alpha)
       mail (>= 2.7.1)
+      net-imap
+      net-pop
+      net-smtp
     actionmailer (7.1.0.alpha)
       actionpack (= 7.1.0.alpha)
       actionview (= 7.1.0.alpha)
       activejob (= 7.1.0.alpha)
       activesupport (= 7.1.0.alpha)
       mail (~> 2.5, >= 2.5.4)
+      net-imap
+      net-pop
+      net-smtp
       rails-dom-testing (~> 2.0)
     actionpack (7.1.0.alpha)
       actionview (= 7.1.0.alpha)
@@ -367,6 +373,10 @@ GEM
     nokogiri (1.12.5)
       mini_portile2 (~> 2.6.1)
       racc (~> 1.4)
+    nokogiri (1.12.5-x86_64-darwin)
+      racc (~> 1.4)
+    nokogiri (1.12.5-x86_64-linux)
+      racc (~> 1.4)
     os (1.1.4)
     parallel (1.21.0)
     parser (3.1.0.0)
@@ -594,9 +604,6 @@ DEPENDENCIES
   minitest-ci
   minitest-retry
   mysql2 (~> 0.5)!
-  net-imap
-  net-pop
-  net-smtp
   nokogiri (>= 1.8.1, != 1.11.0)
   pg (~> 1.1)
   propshaft (>= 0.1.7)

actionmailbox/actionmailbox.gemspec

@@ -39,4 +39,7 @@ Gem::Specification.new do |s|
   s.add_dependency "actionpack",    version
 
   s.add_dependency "mail", ">= 2.7.1"
+  s.add_dependency "net-imap"
+  s.add_dependency "net-pop"
+  s.add_dependency "net-smtp"
 end

actionmailer/actionmailer.gemspec

@@ -39,5 +39,8 @@ Gem::Specification.new do |s|
   s.add_dependency "activejob", version
 
   s.add_dependency "mail", ["~> 2.5", ">= 2.5.4"]
+  s.add_dependency "net-imap"
+  s.add_dependency "net-pop"
+  s.add_dependency "net-smtp"
   s.add_dependency "rails-dom-testing", "~> 2.0"
 end