Very recently I found out that there is a storage limit to the mail you can receive, besides shift codes and pre-order exclusives, and unfortunately lost a Bekah and a Lyuuda both at level 50. Now I know that it’s possible to get the Lyuuda as a world drop, but as of right now the only way to get the Bekah is by finishing Hammerlocks quest line, and I could do the missions again in another level 50 character. My concern in this situation is that quest line rewards should not be overwritten by manufacturer rewards. Some other thoughts are there should be a notification that states when you are approaching your mail limit or state when mail will expire, like it already does for player sent mail.
Now unfortunately I’ve already contacted support and was told that they are unable to restore loot that had disappeared from the mail system. I wanted to share this with the community seeing as I had run out of space in my inventory/bank and wrongfully assumed that it was safe because there was no expiration or mail limit listed. Looking back in hindsight I could have made a mule character to collect these items, but seeing as it has already happened I didn’t want others to experience this.
Tldr: Mail has a limit, roughly 25 manufacturer/quest mail before it will start being overwritten, and there is no notification of you are approaching that limit or if at risk for losing mail.
Feel free to add on to the conversation and happy hunting.