I'm getting the said error when I test the catchall mail I'm using across around 50 projects.
A little more info: just transferred SER on a new dedicated PC, imported settings and projects just fine. When I hit the start button it worked well for about a minute with very high lpm then it started slowing down. I went into a couple of project's settings and tested the mail - the error comes up and I think that's the reason for the low lpm. I tried creating a new project and importing the catchall settings to it - it tests out fine. I tried to re-import the catchall settings into the projects but the error still persists. I'm not sure what the problem could be so any help is appreciated. Thanks.