diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index f17122f4..4c7607c2 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -2545,7 +2545,8 @@ def responses(type = nil)
         when :raise
           raise ArgumentError, "Pass a block or use #clear_responses"
         when :warn
-          warn("DEPRECATED: pass a block or use #clear_responses", uplevel: 1)
+          warn("DEPRECATED: pass a block or use #clear_responses",
+               uplevel: 1, category: :deprecated)
         end
         @responses
       end
diff --git a/lib/net/imap/authenticators.rb b/lib/net/imap/authenticators.rb
index 8ecb3851..5580a335 100644
--- a/lib/net/imap/authenticators.rb
+++ b/lib/net/imap/authenticators.rb
@@ -9,7 +9,7 @@ def add_authenticator(...)
       "%s.%s is deprecated.  Use %s.%s instead." % [
         Net::IMAP, __method__, Net::IMAP::SASL, __method__
       ],
-      uplevel: 1
+      uplevel: 1, category: :deprecated
     )
     Net::IMAP::SASL.add_authenticator(...)
   end
@@ -20,7 +20,7 @@ def authenticator(...)
       "%s.%s is deprecated.  Use %s.%s instead." % [
         Net::IMAP, __method__, Net::IMAP::SASL, __method__
       ],
-      uplevel: 1
+      uplevel: 1, category: :deprecated
     )
     Net::IMAP::SASL.authenticator(...)
   end
diff --git a/lib/net/imap/command_data.rb b/lib/net/imap/command_data.rb
index 20018b5d..71fd4d65 100644
--- a/lib/net/imap/command_data.rb
+++ b/lib/net/imap/command_data.rb
@@ -193,7 +193,8 @@ def validate
 
       def initialize(data)
         @data = data
-        warn "DEPRECATED: #{MessageSet} should be replaced with #{SequenceSet}."
+        warn("DEPRECATED: #{MessageSet} should be replaced with #{SequenceSet}.",
+             uplevel: 1, category: :deprecated)
         begin
           # to ensure the input works with SequenceSet, too
           SequenceSet.new(data)
diff --git a/lib/net/imap/deprecated_client_options.rb b/lib/net/imap/deprecated_client_options.rb
index 1a0fe298..1242bed6 100644
--- a/lib/net/imap/deprecated_client_options.rb
+++ b/lib/net/imap/deprecated_client_options.rb
@@ -83,10 +83,12 @@ def initialize(host, port_or_options = nil, *deprecated, **options)
         elsif deprecated.empty?
           super host, port: port_or_options
         elsif deprecated.shift
-          warn "DEPRECATED: Call Net::IMAP.new with keyword options", uplevel: 1
+          warn("DEPRECATED: Call Net::IMAP.new with keyword options",
+               uplevel: 1, category: :deprecated)
           super host, port: port_or_options, ssl: create_ssl_params(*deprecated)
         else
-          warn "DEPRECATED: Call Net::IMAP.new with keyword options", uplevel: 1
+          warn("DEPRECATED: Call Net::IMAP.new with keyword options",
+               uplevel: 1, category: :deprecated)
           super host, port: port_or_options, ssl: false
         end
       end
@@ -113,7 +115,8 @@ def starttls(*deprecated, **options)
         elsif deprecated.first.respond_to?(:to_hash)
           super(**Hash.try_convert(deprecated.first))
         else
-          warn "DEPRECATED: Call Net::IMAP#starttls with keyword options", uplevel: 1
+          warn("DEPRECATED: Call Net::IMAP#starttls with keyword options",
+               uplevel: 1, category: :deprecated)
           super(**create_ssl_params(*deprecated))
         end
       end
diff --git a/lib/net/imap/response_data.rb b/lib/net/imap/response_data.rb
index 808da9c4..25c1d42c 100644
--- a/lib/net/imap/response_data.rb
+++ b/lib/net/imap/response_data.rb
@@ -939,7 +939,8 @@ def multipart?
       # for something else?
       #++
       def media_subtype
-        warn("media_subtype is obsolete, use subtype instead.\n", uplevel: 1)
+        warn("media_subtype is obsolete, use subtype instead.\n",
+             uplevel: 1, category: :deprecated)
         return subtype
       end
     end
@@ -984,7 +985,8 @@ def multipart?
       # generate a warning message to +stderr+, then return
       # the value of +subtype+.
       def media_subtype
-        warn("media_subtype is obsolete, use subtype instead.\n", uplevel: 1)
+        warn("media_subtype is obsolete, use subtype instead.\n",
+             uplevel: 1, category: :deprecated)
         return subtype
       end
     end
@@ -1111,7 +1113,8 @@ def multipart?
       # generate a warning message to +stderr+, then return
       # the value of +subtype+.
       def media_subtype
-        warn("media_subtype is obsolete, use subtype instead.\n", uplevel: 1)
+        warn("media_subtype is obsolete, use subtype instead.\n",
+             uplevel: 1, category: :deprecated)
         return subtype
       end
     end
diff --git a/lib/net/imap/sasl/cram_md5_authenticator.rb b/lib/net/imap/sasl/cram_md5_authenticator.rb
index 4f33ecc3..df2648da 100644
--- a/lib/net/imap/sasl/cram_md5_authenticator.rb
+++ b/lib/net/imap/sasl/cram_md5_authenticator.rb
@@ -20,7 +20,7 @@ def initialize(user = nil, pass = nil,
                  warn_deprecation: true,
                  **)
     if warn_deprecation
-      warn "WARNING: CRAM-MD5 mechanism is deprecated." # TODO: recommend SCRAM
+      warn "WARNING: CRAM-MD5 mechanism is deprecated.", category: :deprecated
     end
     require "digest/md5"
     @user = authcid || username || user
diff --git a/lib/net/imap/sasl/digest_md5_authenticator.rb b/lib/net/imap/sasl/digest_md5_authenticator.rb
index 1b07c411..13a2fd35 100644
--- a/lib/net/imap/sasl/digest_md5_authenticator.rb
+++ b/lib/net/imap/sasl/digest_md5_authenticator.rb
@@ -161,7 +161,8 @@ def initialize(user = nil, pass = nil, authz = nil,
     password ||= secret || pass or raise ArgumentError, "missing password"
     authzid  ||= authz
     if warn_deprecation
-      warn "WARNING: DIGEST-MD5 SASL mechanism was deprecated by RFC6331."
+      warn("WARNING: DIGEST-MD5 SASL mechanism was deprecated by RFC6331.",
+           category: :deprecated)
     end
 
     require "digest/md5"
diff --git a/lib/net/imap/sasl/login_authenticator.rb b/lib/net/imap/sasl/login_authenticator.rb
index 7496793d..a9686fbe 100644
--- a/lib/net/imap/sasl/login_authenticator.rb
+++ b/lib/net/imap/sasl/login_authenticator.rb
@@ -29,7 +29,8 @@ def initialize(user = nil, pass = nil,
                  warn_deprecation: true,
                  **)
     if warn_deprecation
-      warn "WARNING: LOGIN SASL mechanism is deprecated. Use PLAIN instead."
+      warn "WARNING: LOGIN SASL mechanism is deprecated. Use PLAIN instead.",
+           category: :deprecated
     end
     @user = authcid || username || user
     @password = password || secret || pass