ArgumentError: SMTP To address may not contain CR or LF line breaks: "\"Frank Dietrich\n\" <bits_n_bytes@gmx.de>" (ArgumentError)

[ops-handler]

Error

SMTP To address may not contain CR or LF line breaks: "\"Frank Dietrich\n\" <bits_n_bytes@gmx.de>" (ArgumentError)

          raise ArgumentError, "SMTP #{addr_name} address may not contain CR or LF line breaks: #{addr.inspect}"
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Stack trace

mail/smtp_envelope.rb:51 in validate_addr
mail/smtp_envelope.rb:31 in block in Mail::SmtpEnvelope#to=
mail/smtp_envelope.rb:30 in map
mail/smtp_envelope.rb:30 in to=
mail/smtp_envelope.rb:13 in initialize
mail/network/delivery_methods/smtp_connection.rb:52 in new
mail/network/delivery_methods/smtp_connection.rb:52 in deliver!
mail/network/delivery_methods/smtp.rb:101 in block in Mail::SMTP#deliver!
net/smtp.rb:643 in start
mail/network/delivery_methods/smtp.rb:109 in start_smtp_session

Tracking Details

• Project: exercism-rails
• Sentry: ArgumentError: SMTP To address may not contain CR or LF line breaks: ""Frank Dietrich\n" bits_n_bytes@gmx.de" (ArgumentError)
• Culprit: ActionMailer::MailDeliveryJob
• First seen: Jul 9, 2026