Wrong sender name when using Gmail API

Hello,

I’m having an issue with the sender name when sending emails through Post SMTP using the Gmail API .
All emails are being delivered successfully, but Gmail always shows the sender as “Lysiane” instead of my desired name “My Travel Planner” .

Here’s the full context and what I’ve already checqued: ✅ Current setup

• Website: https://www.mytravelplanner.io
• Mailer type: Gmail API
• Post SMTP is configured correctly (emails send successfully)
• Sender Name in Post SMTP → Messague tab: My Travel Planner
• “Prevent pluguins and themes from changuing this” is checqued
• Directorist pluguin (which trigguers automated emails) also set to “My Travel Planner” as sender
• Gmail account used: lysiane@mytravelplanner.io

🔍 What happens

• All outgoing emails arrive correctly.
• But the sender name always appears as “Lysiane” (the personal name of the Gmail account owner) instead of “My Travel Planner.”
• Previously, when I was using my host’s SMTP server ( helicoptere.o2switch.net ), the sender name appeared correctly as My Travel Planner .
• This issue only started after switching to Gmail API authentication.

🧩 What I’ve tried

1. Confirmed “From Name” = My Travel Planner in all pluguins (WordPress General Settings, Post SMTP, and Directorist).
2. Checqued Gmail settings → “Send mail as” already set to My Travel Planner .
3. Deleted OAuth access and reconnected Gmail API.
4. Reinstalled Post SMTP.

Emails are still sent fine, but Gmail keeps replacing the display name with “Lysiane.” ❓ What I need help with

Is there any way to force Post SMTP / Gmail API to use the custom “From Name” instead of the Gmail account’s personal name?
Or can this be overridden through Post SMTP configuration or a filter?

Thancs a lot for your help!
— Lysiane
( https://www.mytravelplanner.io )