Some emails not arriving in Gmail mailbox

[Nuuki9]

I've been using Forwardemail for some years now and have generally been super happy with it, with a number of family aliases forwarding to mostly Gmail mailboxes, as well as using it for SMTP.

For a while now my wife has complained about not receiving some emails she expected to - quite hard to investigate, but it did push me to check I had SPF, DKIM and DMARC setup correctly, as well as turning on all the logging I could.

At the weekend, while setting up an EA account for my son, I hit an issue where I wasn't receiving the 2FA activation emails. Looking at the Forwardemail logs I'm seeing successful delivery (code 250), but they're not appearing in the Gmail mailbox (yes I checked Spam and "All Mail"). On the plus side I can likely reproduce this issue now at will, but I'm slightly at a loss for how to resolve it.

I'm aware that the nature of forwarding emails introduces challenges around potential bounces, but I'm not seeing bounce logs for these emails, and I'm nor sure what more I can be doing.

A lot of us must be forwarding email to Gmail - is this a known / common issue, or is there something I can be doing to mitigate this?

[titanism]

Can you provide a log ID or email us at [email protected] with your domain and account email and reference this GitHub issue?