How Can CRM Features Boost Your Team's Productivity?
Exploring how CRM features can significantly enhance your team's productivity by optimizing workflows and improving customer interactions.
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2026-09-01
Our project Security
Replies stopped landing in spam: mail-tester 9/10 → 10/10
Gmail put our replies to clients into spam. We found three causes in the mail chain and fixed them in a day.
- Client
- TanSecure · our own infrastructure
- Timeline
- 1 day
- Year
- 2026
mail-check tansecure.com
- $ mail-check tansecure.com
- SPF ✓ pass
- DKIM ✗ missing → ✓ signed (s=mail)
- PTR ✗ mismatch → ✓ matches HELO
- Relay ✗ open for gmail.com → ✓ closed
- DMARC ✓ p=quarantine
- mail-tester: 9/10 → 10/10
10/10
mail-tester score
3
root causes found
1 day
from diagnosis to fix
The problem
Outgoing mail went through Proxmox Mail Gateway and a mail server, and everything looked configured — yet Gmail marked our replies as spam. Clients simply didn't see our offers.
What we did
- 01Traced the full path of a letter: application → Proxmox Mail Gateway → mail server → internet
- 02Created a DKIM key, published it in DNS and restarted the signing service so it actually signs
- 03Set the PTR (reverse DNS) of the server IP to match the mail server name
- 04Configured the gateway's smarthost and removed a foreign domain from relay domains — the gateway had been accepting outside mail for gmail.com
- 05Checked the result with mail-tester using a real text email, not an empty test
Result
- Every outgoing email is signed with DKIM
- SPF, DKIM, DMARC and PTR are consistent with each other
- A hole that let the gateway accept other people's mail is closed
Technologies
- Proxmox Mail Gateway
- docker-mailserver
- OpenDKIM
- Cloudflare DNS
- Hetzner Cloud
Related services
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More cases
All cases →OLX.pl · Marek
Dzień dobry, ile kosztuje konfiguracja poczty firmowej dla 5 osób?
AI draft
Dzień dobry! Konfiguracja poczty dla 5 osób z SPF, DKIM i DMARC zajmuje 1–2 dni. Podam dokładną cenę po krótkim audycie domeny — jaka to domena?
✅✏️🔄🚫
Our project AI & Bots
AI inbox: OLX chats and email answered from one Telegram group
Messages from OLX.ua, OLX.pl and two mailboxes arrive as cards with a reply drafted by AI. One tap sends it — nothing goes out without a person.
4channels in one chat
Read the casetansecure.com/en
enukplde
IT for business: security, sales, automation
- hreflang · en · uk · pl · de · x-default
- schema.org · Organization · Service · FAQPage
Our project SEO
A website in four languages that search engines read correctly
tansecure.com: four versions adapted to each market, 7 directions and 23 services, pre-rendered pages, hreflang and structured data.
4languages
Read the case- 1Order on a marketplace
- 2Stock −1 everywhere
- 3Payment received
- 4E-invoice issued
- 5Label and tracking
Solution example Sales
One stock for Shopify, Amazon and eBay — and invoices that issue themselves
Orders from every channel in one list, stock updated everywhere within a minute, an e-invoice for every paid order.
≤ 1 minstock sync
Read the case
