Few suggestions:
1. Excessive using of bullet points - not easily readable
2. Too much text - it's better to reduce the amount of words or link to the full job description and only leave the key paragraphs (I already see you've attached the full job descriptions but better attach them directly to the message linked to it), like:
- What specialist are you looking for
- Company name
- Location
- Little description of the company's work or of a project
- Requirements, etc.
3. Because of the first two problems, the positions themselves are just missing, fewer people will notice or find them by searching in the channel them at all