When using our email forwarding service, you may occasionally find that some emails land in the recipient’s Spam/Junk folder. This article explains how our forwarding works, why spam can still happen even with proper authentication, and what you can do to improve deliverability.
How Our Email Forwarding Works
All forwarded messages are sent from: forwarded@op-email.eu
To keep reply behavior natural, we set the Reply-To header to the original sender’s address. That means:
- The recipient sees the message from forwarded@op-email.eu.
If they click Reply, their email client automatically addresses the reply to the original sender.
The original sender information is preserved in headers for traceability.
Why this approach?
Using a fixed, authenticated sender ensures strong SPF/DMARC alignment with our domain (op-email.eu), improving consistency across providers.
What We Do to Support Deliverability
- SPF: All outbound IPs are authorized under the SPF record for op-email.eu.
- DKIM: Forwarded messages are DKIM-signed by op-email.eu.
- DMARC: Evaluates against op-email.eu and will pass via SPF or DKIM alignment.
Consistent envelope: A single, authenticated sender reduces false positives with strict filters.
Note: Any original DKIM signature from the source sender may not validate after forwarding because some headers change. The message remains authenticated via our op-email.eu DKIM/SPF.
Why Emails May Still Go to Spam
Email content & formatting: Spam-like language, suspicious links, or risky attachment types can trigger filters.
Original sender reputation: A poor reputation for the original sender’s domain/IP can influence filtering.
Recipient mailbox algorithms: Providers (e.g., Gmail/Outlook) weigh user behavior, past engagement, and proprietary signals.
Low engagement: If recipients rarely open or interact with your messages, providers may downrank future emails.
What You Can Do
- Allowlist: Ask recipients (or their IT) to allowlist op-email.eu or specifically forwarded@op-email.eu.
Mark “Not Spam”: When misclassified, marking as “Not spam” trains the mailbox provider.
Improve content quality: Avoid spammy phrases, link shorteners, or executable attachments; keep a healthy text-to-image ratio.
Encourage best practices: Ask frequent senders to maintain valid SPF/DKIM for their own domain and avoid spam-triggering content.
Consider direct mailbox access: For the highest deliverability control, use IMAP/POP to read the mailbox directly (see below).
Alternative: Use Direct Mailbox Access
For best results and full control (no forwarding involved), connect your email client directly to the mailbox via IMAP/POP3:
Provider-specific help:
Gmail – https://support.google.com/mail/answer/6304825?hl=en
Yahoo – http://help.yahoo.com/kb/SLN28341.html
This avoids forwarding-related heuristics and keeps authentication tied to the mailbox provider end to end.
FAQs
Will recipients always see forwarded@op-email.eu as the sender?
Yes. That’s by design for authentication consistency. Replies will still go to the original sender via the Reply-To header.
Does this pass DMARC?
Yes. DMARC aligns to op-email.eu (the visible From domain). We sign with DKIM and authorize SPF for that domain.
Can we still trace the original sender?
Yes. The original From address is placed in Reply-To and preserved in standard headers so recipients and mail admins can see who originated the message.
