That 'easy' mailbox migration took me 2 days for 12 users

I agreed to move a small office from Yahoo Mail to Office 365. The boss said it'd be a quick afternoon thing (you know, like these always go). Three hours in I realized Yahoo doesn't export contacts in a format O365 can read, so I spent 4 more hours cleaning up CSV files. Then the calendar invite transfer tool just flat out broke on 3 accounts, had to rebuild those manually. In the end it took me about 18 hours total across a weekend. Has anyone else had a supposedly 'simple' migration turn into an absolute nightmare for no good reason?

3 comments

3 Comments

zara_sanchez9d ago

Yahoo to O365 is a special circle of HELL I swear. That CSV stuff is the WORST, I spent hours manually fixing column headers because Yahoo just dumps random fields in there. And the calendar tool? Yeah mine straight up corrupted a PTO series for one user, had to recreate 50 recurring events by hand. For a "simple" 12 user migration the boss probably thought it would take an afternoon but really it's a whole weekend of fixing undocumented garbage.

ray_sullivan9d ago

Ugh, yeah, "undocumented garbage" is exactly the phrase that sums it up. @zara_sanchez that calendar corruption is a nightmare I wouldn't wish on anyone. Rebuilding 50 recurring events by hand sounds like a special kind of punishment. I've had similar luck with the CSV fields just being in a random order. Makes you wonder if Yahoo even tests this stuff before shipping it out. For a small 12 user migration like that, the time estimate is always way off, it's like they think you just flip a switch.

young.ryan9d ago

Saw a post the other day from some MSP who said Yahoo migrations should come with a mental health warning. Totally get that now. One thing I read is that Yahoo's IMAP migration to O365 is actually more reliable than their mailbox export tool but still has weird issues with folder hierarchies. That calendar corruption thing you mentioned happened to a buddy of mine too, he said rebuilding those events made him want to throw his laptop out the window.