Rebecca Armstrong: I'll sponsor your event... if you cough up for mine

What does your email inbox usually look like on a Monday morning? While I'm sure most of us dream of logging on to find a clutch of exciting job offers and a cheering message about Lotto winnings, mine is usually littered with LinkedIn invites (even though I'm pretty sure I visited the site, just once, about three years ago) and special offers from shops I can't remember buying anything from.

There's often another kind of message which, while it doesn't exactly make my heart sink, it doesn't make it soar like the thought of £17m to spend on swimming pools and pet ocelots. "Please sponsor me!!!" its subject line reads. Oh god! I think when I spot it. I then go through the complex internal algorithm that weighs up how much I like the person running/swimming/walking for charity, how near it is to payday, whether what they're raising money for is a cause I support or not and how guilty I'll feel if I don't pay out. But against our worst instincts, we do cough up – fundraising website JustGiving has been used to raise more than £1bn in the 11 years since its launch.

Having conducted an unscientific survey in the office and on Twitter, though, it's clear that everyone has different donation dos and don'ts. One colleague can't bear it when the sponsorship website shows how much you've donated. "Talk about a guilt trip," she sighs. A marathon-running friend says she doesn't sponsor any events that cover less than 40 miles. Harsh. Another mutters about money being raised for rhinos rather than humans.

I like at least one exclamation mark per email for honesty. "I have done ZERO training!" said an email from one friend who was doing a Moonwalk this weekend. "And I might have to use a SheWee in front of my boss." Have £20.

I also like a post-event thank you – after a pal climbed Mont Blanc, he sent a thrilling snap of himself on top of it clutching his ice axe.

I also like my boss's approach of getting workmates to cough up to sponsor her daughter doing Race for Life. "Only open this email if you are kind". Cunning as a fox.

Shilling for sponsorship is a modern minefield thanks to more events and causes than ever before, websites and social networks in place of a sandwich bag full of change and a crumpled form.

So I'm dreading my fundraising drive for a sponsored run next month. I want to find enough cash to meet the £200 minimum, but don't want to lose any friends, which, once I start invading their inboxes with begging emails later today, could be easier said than done.