You can use 7-Zip forums for all common questions; you can get answers on the forums from 7-Zip developers and from other 7-Zip users.
You can send an email message directly to a LZMA developer. Please don't use this form for common questions. Please write only in English.
If you send an email message with questions and you get no answer in 5 days, you can try to send your message via SourceForge system (direct email message / or message to 7-Zip forum).