The ActionMailer railtie's on_load hook applies config.action_mailer.*
settings to ActionMailer::Base when ActionMailer::Base is first
referenced. In our initializer load order, devise.rb runs before
mailer.rb (alphabetical) and triggers ActionMailer::Base loading via
Devise::Mailer. By the time mailer.rb runs, the on_load hook has
already fired with the default :smtp delivery method, and subsequent
writes to config.action_mailer.delivery_method are silently ignored.
Result: production transactional emails (Devise confirmation, password
reset, member invitations) were being sent via Mail's default :smtp
delivery method to localhost:25, raising Errno::ECONNREFUSED on every
attempt — silently in deliver_later. LeadMail was never actually used
despite LEADMAIL_API_TOKEN being set.
Fix is to set ActionMailer::Base.delivery_method (and the matching
*_settings) directly in addition to config.action_mailer.*. Same pattern
applied to the SMTP and sendmail fallback branches for consistency.
Verified locally: rails runner now reports delivery_method=:leadmail
when LEADMAIL_API_TOKEN is set.
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