SMTP error 501 5.1.3 Invalid address


  • Used Zammad version: 5.1
  • Used Zammad installation type: package
  • Operating system: Ubuntu 20.04.4 LTS
  • Browser + version: Firefox 100.x

Expected behavior:

I want to respond to a customer ticket and send a mail to 2 recipients (recipients 1 in the TO field ,recipients 2 in the CC field)

When I sent a E-Mail from Outlook to the 2 recipients , all fine, the mail will delivery correct.

Actual behavior:

In Zammad i get following error message;:

In the log /var/log/zammad/production.log i find following messages:

E, [2022-05-18T11:33:26.717312 #822-181200] ERROR -- : Can't use Channel::Driver::Smtp: #<Net::SMTPSyntaxError: 501 5.1.3 Invalid address
E, [2022-05-18T11:33:26.717351 #822-181200] ERROR -- : 501 5.1.3 Invalid address
app/models/channel/driver/smtp.rb:84:in `send'
app/models/channel.rb:257:in `deliver'
app/jobs/ticket_article_communicate_email_job.rb:56:in `perform'
app/models/scheduler.rb:378:in `block (3 levels) in worker'
app/models/scheduler.rb:376:in `block (2 levels) in worker'
app/models/scheduler.rb:372:in `loop'
app/models/scheduler.rb:372:in `block in worker'
E, [2022-05-18T11:33:26.732377 #822-181200] ERROR -- : Can't use Channel::Driver::Smtp: #<Net::SMTPSyntaxError: 501 5.1.3 Invalid address

Steps to reproduce the behavior:

  1. Open a Ticket
  2. Klick on the replay-button
  3. Write Answer-Mail:
  4. Get error Message

Thanks for any help!


Your screenshots don’t match together.
The reason for your issue is the email address that’s provided in either the TO or CC:

It’s this: email1@domain.tld,email2@domain.tld
That’s one string not two and that’s what your mail server (with all right) does not like.

Hard to tell and help with as this probably depends on the situation and may not affect all tickets.

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