What steps will reproduce the problem?
1. Join a MUC that has history (no mod_muc_mam)
2. Observe delay tags on historic messages
What is the expected output?
<delay from="email@example.com" .../>
What do you see instead?
<delay from="muc.host" .../>
What version of the product are you using? On what operating system?
Please provide any additional information below.
This was fixed in #1054 but seems to have come back in https://hg.prosody.im/trunk/rev/3d3706147174