Kenneth Irving via dovecot:

I see *no* space after msgid=

yes, it's indeed a problem of visiblility. Mailclients as well as the
listarchive tend to break lines exactly there, where it becomes
interesting and additionally they remove the brackets because they are
missinterpreted as HTML tags.

I repeat my Loglines and try to trick a little bit:

# Logs in HTML preformatting

<pre> lmtp(user@example)<22995><RtRIK/YvEWfTWQAAf9UaAw>: Info: save: box=INBOX/ietf/folder1/, uid=14143, msgid= <172917948321.1404061.2617721779338535905@dt-datatracker-78dc5ccf94-w8wgc>, size=7904 lmtp(user2@example.org)<23156><0cjVE809EWd0WgAAf9UaAw>: Info: save: box=INBOX/foo, uid=2632, msgid= <AM0PR06MB4100D06FAD74B7B33BFFDAA395472@AM0PR06MB4100.eurprd06.prod.outlook...., size=16755 lmtp(user@example)<23143><bhcjK288EWdnWgAAf9UaAw>: Info: save: box=INBOX/ietf/folder2/, uid=567, msgid=<62424081-d68e-4334-b9a2-a62d0759cea3@gulbrandsen.priv.no>, size=11394 </pre>

# Logs in Markdown

lmtp(user@example)<22995><RtRIK/YvEWfTWQAAf9UaAw>: Info: save:  
box=INBOX/ietf/folder1/, uid=14143, msgid=  
<172917948321.1404061.2617721779338535905@dt-datatracker-78dc5ccf94-w8wgc>,  
size=7904
lmtp(user2@example.org)<23156><0cjVE809EWd0WgAAf9UaAw>: Info: save:  
box=INBOX/foo, uid=2632, msgid=  
<AM0PR06MB4100D06FAD74B7B33BFFDAA395472@AM0PR06MB4100.eurprd06.prod.outlook....,  
size=16755

lmtp(user@example)<23143><bhcjK288EWdnWgAAf9UaAw>: Info: save:  
box=INBOX/ietf/folder2/, uid=567,  
msgid=<62424081-d68e-4334-b9a2-a62d0759cea3@gulbrandsen.priv.no>,  
size=11394

Andreas