"Reply All" bulk rejection/bounce

[Geoff Gaunt]

Running K9 Version 5.600 on Android 8.1

I've noticed for several months that when using "Reply All" to multiple cc. recipients the reply gets rejected/bounced from the receiving servers

This only happens with K9 - using "Reply All" on my laptop (MS-Outlook) works fine

One of the bounce replies contained the reason described below... 

So it looks like the reply all doesn't send a "from" header causing, them to be rejected as potential spam

>>>>>>>>>>>>>>>>>>>>>>>>>

This is the mail system at host ofarelay01.hostedemail.com.

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

The mail system <nmsilverberg @ googlemail . com>: host gmail-smtp in . l . google . com[74.125.192.27] said: 

550-5.7.1 [216.40.42.17 11] Our system has detected that this message is 

550-5.7.1 not RFC 5322 compliant: 

550-5.7.1 'From' header is missing. 

550-5.7.1 To reduce the amount of spam sent to Gmail, this message has been 

550-5.7.1 blocked.

[Sean Greenslade]

K-9 will definitely send a From: header on all outgoing messages, including reply-all messages. Perhaps you haven't set the account composition defaults. Go to Account Settings -> Sending Mail -> Composition Defaults and make sure everything is filled in correctly.

--Sean

[Gunter Königsmann]

If the server the mail is sent to discards a implausibly-long recipient list and then complains it to be empty?
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.