Your faulty server keeps dropping my login! And, my subscription is due soon! Can i just mail you a check?
(Sorry, didn;t mean to double-post… the SD Gremlin-Zombies got me! 
No, the online portal is the only way to pay.
Sorry you’re having problems, we need a new server. Badly, it would appear. 
Ed talks about it here. Board performance problems - About This Message Board - Straight Dope Message Board
This suspect this is the root cause of all our technical problems of late.
Can’t he just use PayPal to send a payment to the SDMB PayPal account, then send someone (perhaps TubaDiva?) his PayPal confirmation number? That’s how a lot of places handle subscriptions. This would eliminate the need for the board software to work with PayPal.