Could you just temporarily lift the mail size limit for the transition to Yahoo?

I'm checking my mailbox to find messages over 25MB.  I don't know if that's Real Binary MB (1048576) or Marketing MB  (1000000).  And of course the webmail interface has no way to search based on size, so I'm relying on Thunderbird/Outlook to do that.  In some cases they can't agree on how big the attachments are - are you using binary size or MIME-encoded size?

I have a relative handful of messages that shouldn't be there if you were enforcing a 25MB limit before.  Couldn't you just lift it to something like 50MB for the transfer and then knock it back down afterward?  It's a real pain to have to search for and then save these messages elsewhere over an arbitrary limit.